A light source device includes: a laser light source; a circular substrate which has fluorescent body that emits light by using light from the laser light source as excitation light; a wheel motor which rotates circular substrate; a dichroic prism which transmits the light from fluorescent body while reflecting the light from the laser light source; a diffusion plate which diffuses the light from the laser light source; and a plate spring which interconnects diffusion plate and wheel motor.