An anti-shake system includes a movable portion to which an optical element is mounted; a support member which holds the movable portion in a manner to allow the movable portion to move freely in directions orthogonal to an optical axis; and a drive system which drives the movable portion in the directions orthogonal to the optical axis. A natural frequency of the movable portion that originates from the movable portion and the support member is set within the range of frequencies of shaking of an apparatus equipped with the anti-shake system which is caused by hand shake.