Reflector mounting structure and projection display device

A reflector mounting structure includes a reflector and a fixing member. The reflector includes: a reflecting surface; a reflector body having the reflecting surface formed thereon; a pair of first connecting units provided respectively at an end face of the reflector body and having a substantially spherical first protrusion at an end thereof; and a second connecting unit provided at an end face of the reflector body. The fixing member which supports the reflector includes a pair of first supporting units respectively having a planar contact portion and bringing the contact portion into contact with an end of the first protrusion, and a second supporting unit. A contact-portion vertical distance is set such that the first protrusion moves while rolling with respect to a contact portion when the reflector deforms.