PURPOSE: To obtain a semiconductor device which does not require so many input/output pins for tracing and also to attain a diagnostic system for the semiconductor device.

CONSTITUTION: The data for tracing on a semiconductor device 10 received from an address register 2 are stored in a RAM 4 and then read in parallel and for each surocessively from the RAM 4 to a read register 5. These read trace data are outputted through a terminal 63 as the serial data. When plural devices 10 are prepared, the output of the terminal 63 is supplied to the terminals 64 of the devices 10 contiguous to each other. Then the outputs of other devices 10 contiguous to each other are received at the terminals 64. Thus the trace data are successively shifted and supplied to a diagnosing device.