A program verification system includes a PLC that calculates control output data corresponding to control input data by using a control program for controlling an apparatus to be controlled, and outputs the control output data to an input/output device, and a collation unit that performs operation verification of the control program by collating test output data included in a test pattern, which is a combination of test input data and the test output data satisfying operation specifications of the apparatus to be controlled and indicates a temporal change, with the control output data calculated by the PLC, and the PLC includes a control unit that, when operation verification of the control program is performed, if there is an instruction to refer to the control input data in the control program, generates first time information in the PLC, extracts the test input data corresponding to the first time information from the test pattern, and calculates control output data by using the extracted test input data and the control program.