An objective lens actuator is provided which includes two objective lenses mounted on a movable body, and which is capable of preventing the movable body from coming into contact or collision with a disk and whose thickness becomes thinner. When a light beam is concentrated and focused on a high-density optical disk, D1 represents the distance between the disk surface and the part of the movable body in the closest position to the disk; when a light beam is concentrated and focused on a CD, D2 represents the distance between the disk surface and the part of the movable body in the closest position to the disk; when a light beam is concentrated and focused on a DVD, D3 represents the distance between the disk surface and the part of the movable body in the closest position to the disk; and the following relational expression (1) is satisfied, D1