An optical image stabilizer of the present invention is mounted in a camera at an image size of a lens to assist an image capture device. The optical image stabilizer includes a base, a transverse frame, and a longitudinal frame. The base is provided with a pair of transverse rails and longitudinal reference magnets. The transverse frame is engaged with the transverse rails for reciprocation and is provided with a pair of longitudinal rails, transverse reference magnets and longitudinal reference magnets, wherein the longitudinal reference magnets are between the longitudinal rails. The longitudinal frame is engaged with the longitudinal rails for reciprocation and is provided with the image capture device, a transverse drive coil, and a longitudinal drive coil. The longitudinal drive coils are between the longitudinal rails and in association with the longitudinal reference magnets that the longitudinal frame may move smoothly.