An embodiment of a light source device according to the invention includes: a light source unit configured to emit light; a first optical element on which the light emitted from the light source unit is incident; a first drive unit configured to rotate the first optical element; and a control unit configured to control the light source unit and the first drive unit. The control unit is configured to continue rotating the first optical element during a first period until a first predetermined time passes after the light source unit is turned off.