PURPOSE: To generate test data on a printed board where a small analog circuit is mounted together with a digital circuit at a high speed by providing a simulator with analyzing circuit software for simulating the analog circuit.

CONSTITUTION: The input signal generation part 12 of the test data generating device 60 supplies a specific test pattern H- or L-level signal to the digital circuit 30 of a circuit model 10M. In the model 10M, the analog circuit 32 consisting of a CR type delay circuit is provided and the output signal of the circuit 30 is supplied to a digital circuit 34 through the circuit 32. A gate level simulator 11D performs only the H/L-level simulation of the circuit 30. Only the H/L-level simulation of the circuit 32 is also performed while diffraction analytic software 11A is in DC analytic mode, the output signal obtained by the composite simulation of the both is inputted from an output signal input part 14 at sufficiently stable timing and recorded 36 at a recording part 16, and the test data is generated with the recorded data.