To provide a counting device and a counting method capable of drastically reducing power to be consumed in an internal circuit and stabilizing a counting operation by power from an input pulse.

Read operation processing and write operation processing are carried out in the same cycle, the data of a count value to be stored in a nonvolatile memory 24 are stored in format of a gray code to thereby reduce the processing time of reading or writing the data from/in the nonvolatile memory 24, and the number of bits that changes before and after increment made by an increment circuit 26 is always limited to be one bit.