I (17, boy) have a girlfriend. She just went to a gynecologist, that’s a women’s doctor. The doctor says that all girls have to go there. Is there also a men’s doctor?

Yes, there is such a doctor.
This doctor is called “andrologist”.
Usually they are also urologists at the same time.
You can see this doctor for lots of things.
When you have questions about sex or about your body.
When something seems strange about your penis.
When you are insecure because your body is changing.

What is important:
You can always go there by yourself.
The doctor can give you a check-up.
If that is what you want.

It is good to know your body.
That way you notice changes.
For some changes, you have to see a “urologist”.
For example if you had hard lumps on your testicles.
That should be looked at by a doctor.
Here is how you can find a doctor near you: