A laser beam from a pickup is focused on an information recording medium, such as a DVD-R/RW, to record information. When the power of the laser beam is calibrated, the laser beam emitted from the pickup is received by a light receiving unit such as an FMD. The level of the received laser beam is detected, the power ratio of the laser beam is determined based on the result, and the power of the laser beam is calibrated so that the power ratio matches a predetermined reference power ratio. This method enables information to be recorded with optimum recording characteristic because the reference power ratio shows the power ratio for recording information at the optimum characteristics.