To provide a diaphragm feather in which inconvenience such as flare or ghost does not occur.

A diaphragm feather 21 includes a feather substrate 21w, and a feather end face 21u that is the end face of the feather substrate 21w and that forms an aperture diameter. The feather end face 21u includes a first inclination part 21p that is curved and inclined with respect to an optical axis O, a first tip part 21q forming the tip of the first inclination part 21p, a second inclination part 21r that is curved and inclined in approximately the same direction as the first inclination part 21p so as to be overlapped with the first inclination part 21p with respect to the optical axis O, and a second tip part 21s forming the tip of the second inclination part 21r. The first tip part 21q is projected on the side of the optical axis O compared to the second tip part 21s.