A joy stick mechanism for an ophthalmic apparatus moving an optical device of the ophthalmic apparatus horizontally and vertically, which mechanism is simple in structure but excellent in operational efficiency. Therefore, this mechanism comprises a drive device for moving the optical device vertically, a rotating knob rotatably provided on a shaft which substantially extends through a central portion of the mechanism, a detection device for detecting a direction and an amount of rotation of the rotating knob, and a control device for controlling the drive device on the basis of detection results of the detection device.