PURPOSE: To evaluate an A/D converter with high accuracy independently of the type of the A/D converter by synchronizing an input timing of measured data with the converting operation based on characteristic data stored in advance corresponding to the type of the A/D converter to be evaluated.

CONSTITUTION: A ROM 38 connected to a digital signal control circuit 22 stores in advance characteristic data for each type of a measured A/D converter. When a type of the A/D converter is designated and the start of the measurement is commanded, a timing control circuit of a data sampling synchronization circuit 36 stores the characteristic data in its internal register and compares the data with the inputted measured data and outputs an interrupt signal while synchronizing with the operating timing of the measured A/D converter, and also generates a strobe signal synchronized with the generating timing of the control signal and conversion data of the measured A/D converter, stores and outputs newly measured, data to a bus 24 every generation of the strobe signal and a digital signal control circuit 22 stores sequentially measured data to a RAM 28 in a timing synchronously with the interrupt signal.