PURPOSE: To enhance the reliability of an apparatus for generating an LSI test pattern automatically.

CONSTITUTION: The LSI test pattern generating apparatus comprises a waveform information extraction unit 11a for generating indeterminate information 16 and waveform information of such period as containing no indeterminate value using signal variation information 3 and signal line information for every period, and an indeterminate value waveform information extraction unit 17 for generating waveform information 6a of such period as containing an indeterminate value using the indeterminate value information 16 and the waveform information 6a of such period as containing no indeterminate value. Consequently, the waveform information of such period as containing an indeterminate value can have waveform type and waveform timing identical to those contained in the waveform information of such period as containing no indeterminate value.