A light source apparatus includes a light source unit in which a light source and a light source supporting member having elasticity in an optical axis direction are coupled together, and a collimating lens base member on which a collimating lens is supported. An optical axis direction adjusting member is positioned between the light source unit and the collimating lens base member. A position of the light source unit can be adjusted within a plane approximately perpendicular to the optical axis, and the light source unit can thereafter be secured relative to the collimating lens base member via the light source supporting member. The optical axis direction adjusting member is movable in the optical axis direction, and is disposed such that by its movement it causes the light source supporting member to deform against the elasticity of the light source supporting member, thereby allowing an adjustment of a position of the light source with respect to the collimating lens in the optical axis direction.