In a case where (i) a reflectance calculated from a reflected light amount obtained from a longest pit (P1max) or a longest space (S1max) in a first pit row is defined as a first reflectance and (ii) a reflectance calculated from a reflected light amount obtained from a longest pit (P2max) or a longest space (S2max) in the second pit row is defined as a second reflectance, the first pit row is formed such that the first reflectance becomes substantially identical with the second reflectance.