A processing-in-memory (PIM) device includes a data storage region and an arithmetic circuit. The data storage region is configured to store first data and second data. The arithmetic circuit includes a multiplier for performing a multiplying calculation of the first data and the second data. The arithmetic circuit is configured to perform a multiplication/accumulation (MAC) arithmetic operation of the first data and the second data. The arithmetic circuit includes a zero-detection circuit configured to disable input of the multiplier and to output zero data including multiple bits having a value of ‘0’ as output data of the multiplier, when all bits included in at least one of the first data and the second data have a value of ‘0’.