PURPOSE: To obtain a PCM codec, and s test method therefor, in which the output data from an A/D (analog/digital) conversion output section can be tested in a short time.

CONSTITUTION: A PCM codec is provided, at the A/D conversion output section thereof, with an offset circuit 2 for imparting an offset to a parallel data outputted from an inner circuit 1 depending on a control signal for switching an actual operation mode and a test operation mode selectively only at the time of test operation, and a P/S (parallel/serial) conversion circuit 3 for converting the output therefrom into a serial data. Since the process for imparting an offset to a serial data outputted from a PCM codec can be eliminated in a tester for testing the PCM codec, the test time can be shortened significantly.