PURPOSE: To provide the sequence program check device capable of easily check whether or not a sequence program is proper, specially, for a ladder chart type programmable sequence controller.

CONSTITUTION: Input data showing the operation of at least the sequence program and at least one position and output data corresponding to the input data are set by an operation means OP, and the set input data and set output data are stored in a storage means ME according to the order of operation that the sequence program stored in the mounted programmable controller MP should perform. Then execution output data when the mounted programmable controller MP is driven, on the basis of the sequence program corresponding to the set input data stored in the storage means ME are taken out and collated with the set output data stored in the storage means ME by a collation means CM. Then a display means DS displays the operation state of the operation means OP and also displays the collation result of the collation means CM.