A one-hot data generating unit generates one-hot data for the maximum data bit width in which a state of one bit is exclusively inverted with respect to states of other bits while sequentially shifting a bit position to be inverted, and writes the one-hot data in an area of a memory designated by an address. A short defect between wirings connected to the memory is detected by comparing the one-hot data written in the memory with the one-hot data before being written.