Optical disk apparatus, method for controlling the same, and recording medium

The present invention provides an optical disk apparatus in which a first, second, third, and fourth optical disks are selectively installed, the first and second optical disks having different recording film characteristics and both having a single-layer recording layer, the third and fourth optical disks having different recording film characteristics and both having a double-layer recording layer. A control section (420) determines which of the first to fourth optical disks has been installed, on the basis of the level of a reproduction signal from an optical head (402). Recording media serving as the optical disks are formed so that the light reflectances of a single-layer L-H medium in an initialized state, an L0 layer of a double-layer H-L medium in the initialized state, and an L0 layer of a double-layer L-H medium in an uninitialized state do not overlap the light reflectance of a single-layer H-L medium in the initialized state.