To reduce the thickness of a light shielding device in an optical axis direction while preventing the weight of all the aperture blades from being excessive.

The area of an aperture 1g formed on the optical axis is changed by plural light shielding blades 4 to 8 which are arranged in plural positions in the optical axis direction and which are freely moved in planes orthogonally crossed with the optical axis. Among the light shielding blades 4 to 8, the 1st light shielding blades 5 and 7 formed only of resin material and the 2nd light shielding blades 4, 6 and 8 formed by at least partly using metal material are mutually arranged in the optical axis direction, and projecting parts 4c, 4d, 6c, 6d, 8c and 8d are formed on the 2nd light shielding blades 4, 6 and 8 so that the projecting parts may come in slidable contact with the 1st light shielding blades 5 and 7, or supporting members 1 and 3.