The width W of the address pit (9) of an optical recording medium of intermediate address type is determined by W=k Tp/(.lamda./NA) where .lamda. is the laser wavelength of the optical head of the optical disk device use, NA is the numerical aperture of the objective, Tp is the track pitch of the record medium, and k is 0.40.ltoreq.k.ltoreq.0.68. Alternatively, an optical device comprises a first address demodulating circuit for demodulating address information by using a signal that is the sum of the electric signals outputted from a pair of photodetectors separated in the direction of the track and a second address demodulating circuit for demodulating address information by suing a signal that is the difference between the electric signals. The address is detected base on the information thus obtained. In such a way, the compatibility of the recording medium used and that of the optical device are improved, the reproduction margin in demodulating the address information is increased, realizing high accuracy address detection when reproducing data from an optical recorded medium of intermediate address type.