The camera is not rotated correctly. What's wrong?

Question

C++ / C#

I am writing a simple game in Unity using C#. I need to implement camera rotations with the mouse, I do it like this:

transform.Rotate(-Input.GetAxis("Mouse Y"), Input.GetAxis("Mouse X"), 0, Space.World);

I move the mouse horizontally - everything is correct, I move it vertically - the camera rotates along the Z axis, not Y. What am I doing wrong?