Image pickup apparatus including dust resistant walls

The image pickup apparatus includes an image taking optical system, an optical filter into which the light from the image taking optical system enters, an image pickup element electrically converting the optical image formed by the light that has passed through the optical filter, an image pickup element holding member holding the image pickup element together with the optical filter, and a lens holding member holding an image surface side lens unit disposed closest to the optical filter. The lens and image pickup element holding members are moved relatively to each other in an optical axis direction, and include dust-proof walls that surround a space between the image surface side lens unit and the optical filter and mutually overlap in a direction orthogonal to the optical axis direction in an entire range where the lens and image pickup element holding members are relatively moved.