The invention provides a projection display apparauts, which projects projection light for displaying an image onto a projection surface. The projection display apparatus includes a light source unit,a light deflector, a first light receiver, a second light receiver, and a calculator. The light deflector deflects at least part of incident light coming from the light source unit to a first opticalpath so as to produce a projection light, and deflects a remaining part of the incident light to a second optical path. The first light receiver receives the at least part of the incident light thathas been reflected by the projection surface. The second light receiver receives the remaining part of the incident light. The calculator calculates a distance from the projection display apparatus toa projection surface based on light reception results obtained by the first light receiver receiving the at least part of the incident light and the second light receiver receiving the remaining partof the incident light.