To provide a blade driving device for an imaging apparatus capable of selectively obtaining a two-dimensional image and a three-dimensional image even when an independent aperture switching device for switching between one aperture for a two-dimensional image imaging and two apertures for a three-dimensional image imaging is not included.

Eight pieces of blades 7 to 14 are attached to blade attaching shafts 1b to 1i of a bottom board 1 to be capable of rotation. One rotor 15 has four pieces of blades 7 to 10 advance into/retreat from an aperture section 1a and when advancing, an elliptic aperture is formed on a right side of an optical axis by aperture forming edges 8c, 9c of the blades 8, 9. Furthermore, the other rotor 16 has four pieces of blades 11 to 14 advance into/retreat from the aperture section 1a and when advancing an elliptic aperture is formed on a left side of the optical axis by aperture forming edges 12c, 13c of the blades 12, 13. Imaging of the two-dimensional image is carried out by fully opening the aperture section 1a and imaging of the three-dimensional image is carried out by alternately forming two elliptic apertures.