The optical image stabilizer includes a shift member holding an image stabilizing element and being movable with respect to a center axis, a lock member disposed around the shift member and rotatable about the center axis between a lock position to limit movement of the shift member and an unlock position to release the limit of the movement of the shift member, and a base member including a supporting portion to rotatably support the lock member. The shift member includes protrusions at its plural circumferential places. The lock member includes, in its inner circumferential part, locking portions to receive contact of the protrusions at the lock position so as to limit the movement of the shift member. The supporting portion is formed so as to include plural openings allowing contact of the protrusions with the lock portions and so as to support the inner circumferential part of the lock member.