A light amount adjustment device including a motor which can be reduced in size by reducing radial and axial dimensions and makes it possible to increase the motor output. The device has a stator of a motor drive mechanism formed integrally with a holding member fixed to a cam member with aperture blades and a rotary member for driving them sandwiched therebetween. A stator includes a support portion, and first and second magnetic pole portions. The first and second magnetic pole portions extend toward an outer periphery of the rotor and coils are inserted thereon from respective extending ends. The extending ends are disposed in a manner opposed to the outer periphery of the rotor. The two portions are disposed with an angle therebetween such that respective lines extending in the extending directions intersect with each other.