An image stabilizer includes a guide device which guides an image-stabilizing optical element in a direction orthogonal to an optical axis and an image shake counteracting driving device, the image shake counteracting driving device including a drive source; a first moving element; a second moving element capable of transferring a moving force of the first moving element to a holder which holds the image-stabilizing optical element; and a mutual guiding device which couples the first and second moving elements to allow the first and second moving elements to move relative to each other in the guide direction. The mutual guiding device includes two first slidable portions provided at two different positions in a direction orthogonal to the guide direction, respectively; and one second slidable portion provided at a position different from the positions of the two first slidable portions in the guide direction.