PROBLEM TO BE SOLVED: To provide an optical recording medium which can excellently record even with a short wavelength laser beam, clarify an optical constant required to a recording layer, in particular, a value of a real part (refractive index) of a complex refractive index and a variation in refractive index before and after recording, and is excellent in recording characteristics. SOLUTION: A second optical recording medium 10B is provided with a second substrate 24, a second write once type recording layer 26 formed on the second substrate 24 and a second light-reflecting layer 30. The second write once type recording layer 26 is irradiated with laser light 46 having a wavelength of 450 nm or shorter to record/reproduce information. In this case, the real part of the complex refractive index of the second write once type recording layer 26 is 1.2-1.5 before the information is recoded to the second write once type recording layer 26 with the laser light 46, and the real part of the complex refractive index of the second write once type recording layer 26 is 1.7-1.9 after the information is recoded to the second write once type recording layer 26 with the laser light 46. COPYRIGHT: (C)2008,JPO&INPIT