A projection apparatus comprising: a housing; a power supply; a light source; a control unit; and a projection lens attached to the housing, the projection lens having a holder (31, 40, 50), a detection unit (70A, 70B) that detects a rotation state of the holder, an emission optical system, and a locking mechanism unit (60A, 60B) that brings rotation of the holder into a locked state or an unlocked state, wherein the projection lens is displaceable by rotating the holder, between a first position at which a rotation state of the holder is a housed state in which an extending direction of an optical axis of the emission optical system faces the housing and a second position at which the extending direction does not face the housing, wherein the second position includes an upper position at which the emission optical system faces an upper side in a vertical direction, wherein the control unit keeps the light source turned off in a case where the power supply is turned on in a state where the holder is at the first position, or the control unit turns off the light source in a case where the projection lens is displaced from the second position to the first position in a state where the light source is turned on, and wherein the control unit turns on the light source, in a case where the power supply is turned on and the projection lens is at the upper position; and wherein the holder has a first holder through which light of a first optical axis emitted from the light source passes, a second holder through which light of a second optical axis obtained by bending the first optical axis passes, and a third holder through which light of a third optical axis obtained by bending the second optical axis passes, wherein the second holder rotates around the first optical axis, and the third holder rotates around the second optical axis, wherein the projection lens is movable to the first position and the second position by a rotation of the third holder. a housing; a power supply; a light source; a control unit; and a projection lens attached to the housing, the projection lens having a holder (31, 40, 50), a detection unit (70A, 70B) that detects a rotation state of the holder, an emission optical system, and a locking mechanism unit (60A, 60B) that brings rotation of the holder into a locked state or an unlocked state, wherein the projection lens is displaceable by rotating the holder, between a first position at which a rotation state of the holder is a housed state in which an extending direction of an optical axis of the emission optical system faces the housing and a second position at which the extending direction does not face the housing, wherein the second position includes an upper position at which the emission optical system faces an upper side in a vertical direction, wherein the control unit keeps the light source turned off in a case where the power supply is turned on in a state where the holder is at the first position, or the control unit turns off the light source in a case where the projection lens is displaced from the second position to the first position in a state where the light source is turned on, and wherein the control unit turns on the light source, in a case where the power supply is turned on and the projection lens is at the upper position; and wherein the holder has a first holder through which light of a first optical axis emitted from the light source passes, a second holder through which light of a second optical axis obtained by bending the first optical axis passes, and a third holder through which light of a third optical axis obtained by bending the second optical axis passes, wherein the second holder rotates around the first optical axis, and the third holder rotates around the second optical axis, wherein the projection lens is movable to the first position and the second position by a rotation of the third holder.