To provide an auto-focusing device capable of preventing a focal position which is not desired by a user from being auto-focused even though hand shaking occurs.

When the occurrence of hand shaking is predicted, or when the occurrence of hand shaking is detected, the shape of an AF block 14 being originally a quadrilateral is changed to make end parts of the shape thin so that another object 13 is hard to come into the AF block 14. Concretely, the shape of the AF block 14 is changed into an AF block 14 of a polygon, wherein the number of angles is more than that of an unchanged AF block and angles at end parts of both sides are an acute angle. Thus, it is possible to realize an auto focus device capable of preventing an auto focus from being made at a focal position that is not desired by the user.