An imaging apparatus includes of a lens holder arranged concentrically with an imaging element; a lens barrel having an imaging lens removably inserted from the leading end section side of the lens holder; a cover removably fitted at the leading end section of the lens holder; and a cam mechanism section arranged on the barrel, the lens holder and the cover so that the barrel turns around the optical axis to the imaging element and that the barrel moves in the optical axis direction. The cam mechanism section includes a first cam surface formed on the inner circumference surface of the lens holder; a cam protruding section formed on the outer circumference surface of the lens barrel; and a second cam surface formed on the inner surface of the cover. The cam mechanism section smoothly turns the barrel around the optical axis and moves the barrel in the optical axis direction.