Within a lens-tube main body, the light-shielding member is fixed to a second lens frame in a second portion opposite to a first portion in which an image forming panel is shifted from an optical axis with the optical axis positioned therebetween. Since the light-shielding member is fixed to the second lens frame in the second portion, heat caused by the unnecessary light is distributed from the first portion to the second portion within the light-shielding member. Accordingly, a local temperature rise is suppressed, and deformation of a lens-tube main body is suppressed. Accordingly, tilt of lenses due to deformation of the lenses does not occur, and deterioration in resolution of the entire image caused by the tilt of the lenses or the occurrence of focus position shift in a diagonal direction due to the occurrence of field curvature is suppressed.