You don't have to say "branch office", but you can simply say that it is a "branch."
You can also use the metaphor of a satellite, ie a "satellite location" or a satellite operation, which are small locations for the main office. A "satellite" is a celestial object the orbits a planet or star, and it is smaller than the planet or star. In this metaphor, the main office is the large planet or star and the branch is the orbiting satellite.
「支店」は英語で「branch」や「branch office」といいます。
I work at the Osaka branch office.
（私は大阪支店で勤務しています。）
The Kyushu branch office will soon close permanently.
（九州支店はもうすぐなくなります。）
My company has branches all over the country.
（私の会社は全国に支店があります。）
Branch - A division or office of a large business or organization, operating locally or having a particular function.
‘He went to work at our Birmingham branch.’
If there is a name for the site or area where this office is located, you could identify the office by the area or site name.
"Would you please call into the Manchester office and see what the problem is?"
"Please call the Manchester branch and tell them to cancel the order."
Branch （支店）
-会社や組織などの現地支店や部署や事務所
‘He went to work at our Birmingham branch.’
（彼はバーミンガム支店に働きに行きました）
その支店がある場所の名前があれば名前でどこの支店か確認することが出来ます。
"Would you please call into the Manchester office and see what the problem is?"
（マンチェスターオフィスに電話をかけて何が問題か確認してくれますか？）
"Please call the Manchester branch and tell them to cancel the order."
（マンチェスター支店に電話をかけて注文をキャンセルするように伝えてください）
We use the word 'branch' when we talk about an office of a company that is not its headquarters. The word branch is used as a metaphor. Think of a tree. It has a main base then many branches coming off, making it bigger!
A larger company will have smaller offices in different places to provide service.
Normally, people will say "branch" for short.
Ex. "There are two branches in this town."
Ex. "The bank has multiple branches around the state."
大きな会社はいろいろなところに事務所を設けています。サービスを届けるためです。
普通は「branch」と短く言います。
例）There are two branches in this town.
（この街には2つの支店がある。）
例）The bank has multiple branches around the state.
（その銀行は州のあちこちに支店を持っている。）
A branch, division or subdivision could all be used to describe an office that is a small part of a larger organisation.
For example: "I need to go to a local branch of my bank"
"This office is a division of my company"
"branch", "division" や"subdivision"は、これらすべて大きな組織の小さな事務所、支店の事を言い表すことに使うことが出来ます。
【例】
"I need to go to a local branch of my bank"
（私の銀行の地方支店に行かなければなりません）
"This office is a division of my company"
（この事務所は私の会社の支店です）
A branch office is an office that is located away from where the head office of a company is located. The branch office carries out duties that the head office assigns to it. It serves a particular area which is not serviced by the head office but normally has an accounting office that is responsible for accounting activities involving the branch. The branch office reports to head office on a regular basis. So, if you are the manager there, you may say:
I am the branch manager at the branch office of (name of company).
or
As the branch manager, I manage everything at the branch office.
"Branch office"とは会社本部から離れた場所にあるオフィスのことで、つまり「支店」の事を意味します。
"Branch office"は本部の指示に従って業務を行います。
支店は本部により全てを管理されていないこともあり、支店の会計を管理するために会計事務所がやとわれていることもあります。
支店は本部と密に連絡を取り合います。
もし、あなたがマネージャー（責任者）でる場合などは、以下のように言うことができるでしょう。
I am the branch manager at the branch office of (name of company).
（私は～会社支店のマネージャーです。）
As the branch manager, I manage everything at the branch office.
（支店のマネージャーとして支店内全ての管理は私が行います。）
There are many ways to describe an office that is not the main head quarters. Sub refers to an office that is less important usually with fewer functions than the main office like a sub-post office in the UK.
The word you choose will depend really on the size of the company and their company structure.
In the UK it tends to be Head office for the main most important office of the company and branches for the smaller offices.
Words like branch, office, agency tend to be the most popular and often the town or city will be used to identify the offices. e.g Our Tokyo office.
Words like division, subdivision, wing are more appropriate for the huge multi national companies.
本社ではなく「支店」を表すフレーズはたくさんあります。
Sub=本部より会社として担うことがすくないオフィス（支店）の事です。
Sub-post office in UK= イギリスにある郵便局の支店
どの単語を使って「支店」を表すのかは、会社のサイズや会社の構造などによります。
イギリスでは、Head officeが本部、本社、branchが支店（本社よりちいさい規模のオフィス）のことを意味します。
branch, office, agency などという単語が支店を表すには適しているでしょう。～支店という場合は、Our Tokyo office（東京支部・支店）のように頭に場所をつけてどこにある支店かを伝えます。
division, subdivision, wingなどの単語は、大企業内での部署の分け方などに使うと適切でしょう。
支店は英語で branch office と言います
例）
新宿支店で働いています
I'm working at the Shinjuku branch office
原宿にも支店がある
There's also a branch office in Harajuku
ちなみに本店は main office と言います。
ご参考になれば幸いです。
"branch"は「支店」を意味します。"office"と言わなくても「支店」のことだと理解しやすいです。
"branch office"も「支店」を意味します。これは事務所である支店に限っています。例えば、レストランの支店は"office"と言われたら違和感を感じます。
"(city name) + office"のパターンで言えば、"branch"と言うまでもなくなります。私は自分の職場を説明しているなら、こう言うと思います。
また、"one of the (company name)'s offices"は「支店」の間接的な言い方です。どの支店で働いているかを言いたくない場合は、この言い方を勧めます。
例文一：
I work at the Nagoya branch.
名古屋支店で働いている。
例文二：
I work at the Nagoya branch office.
名古屋支店で働いている。
例文三：
I work at the Nagoya office.
名古屋支店で働いている。
例文四：
I work at one of the company's offices.
会社の支店で働いている。
Most cases this is considered a branch office. It is still under the same umbrella as the headquarters. It can be at a location away from the campus of the company. Or it could be a satellite office and only report electronically to the main office.
if you would like to know what you can call an office of a company that is not the headquarters/main building/main office, you can call it a "branch office" or a "sub-office". You can use it in a sentence by saying something like "You can go to our branch office to pick up the paperwork.".
Branch can mean there are multiple branches. This is where normally a large company will have smaller offices to help with their daily work.
- Go to the South branch to pick up your paperwork.
The two sentences you see provided above are great ways to express to your listener that you work at an office that is not the headquarters of your company. In the first sentence you will see the word division and in the second sentence you will see the word branch. Both of these words mean a part of a company that is not located at the main headquarters. These words would make great additions to your vocabulary.
We can use either the words, "branch office," or, "company's office," to refer to an office space that is owned by a particular company, but is not the main headquarters of that office.
Example sentences :
- I work in a branch office in Japan, the actual headquarters is located in China.
An office of a company that is not located where the main building/office/ headquarters are, then you may use the following terms:
-Satellite office
-branch office
You may use the above terms in the following ways:
-Our company's marketing team works from a satellite office and not at our headquarters.
-The branch office is very important because legal and marketing works from there.
アメリカ合衆国 
イギリス 
南アフリカ 
