A method of reproducing an optical disk that that shortens the time between optical disk insertion and implementation of a standby mode enabling reproduction is provided that comprises a step of reading parameters stored in a nonvolatile memory, a step of deciding whether the optical disk can be properly reproduced using the read parameters, a step of, when it is found that the optical disk cannot be properly reproduced using the parameters, conducting a focusing search, reflection level detection, tracking error signal amplitude measurement and the like with respect to the optical disk, a step of specifying new parameters based on the result, and a step of storing the new parameters in the volatile memory.