PURPOSE: To obtain a failure simulation device capable of automatically extacting a signal line having the probability of generating a short-circuit failure and executing failure simulation for the extracted signal line.

CONSTITUTION: A wiring information extracting means 2 extracts wiring information from layout data 1. A short-circuit failure generating position specifying means 4 specifies a signal line whose short-circuit failure is to be detected based upon the extracted wiring information and a failure generation condition described in a failure generation condition file 3. A short-circuit simulation executing means 5 executes short-circuit failure simulation while supposing the generation of a shirt-circuit failure on the specified signal line. A short- circuit failure error information output means 6 outputs the simulation result as an error information list 7. Consequently a signal line to be failed can be specified by a uniform reference and the misinput of the signal line to be failed can be prevented. In addition, failure simulation execution time including preparation for the execution can be shortened.