When an access device accesses a nonvolatile memory device, the nonvolatile memory device or the access device detects or calculates a temperature T of the nonvolatile memory device. A temperature-adaptive control part of the nonvolatile memory device controls an access rate to a nonvolatile memory on the basis of the temperature T. Accordingly, the control part controls the rate so that the temperature T of the nonvolatile memory devices cannot exceed a limit temperature Trisk. In this manner, a nonvolatile memory system can eliminate a risk of a burn when ejecting the semiconductor memory device and can read and write data at a high speed.