An information recording medium 100 according to one aspect of the present invention includes a disc substrate 1 formed by a resin, and a thickness thereof in a data area 102 is 0.2 mm or less. The information recording medium 100 includes a step 110 in an inner periphery area 101, the step having a height of 1 mm or more and 3 mm or less. The step 110 includes an acute-angle edge portion 111 used for positioning a center of the information recording medium 100 when spinning the information recording medium 100; and an angle θ of an inner side of a cross section of the acute-angle edge portion 111 is 50 degrees or more and 80 degrees or less.