An optical disk recording/reproducing apparatus includes at least a focus shift mechanism for controlling a lens to focus a laser beam on a disk so as to form a beam spot on the disk, a reproduced signal evaluator for evaluating the quality of the reproduced signal on the basis of the output from a reproduced signal detector, a controller for setting the operation target point of the focus shift mechanism, where the best quality of the reproduced signal is attained, on the basis of the output from the reproduced signal evaluator, and an offset generator circuit for outputting a focus offset signal in response to a command from the controller. The operation target point of the focus shift mechanism is set to the optimal point where the jitter in the reproduced signal is rendered minimum.