According to the present invention, an input operation unit receives an input related to generation and editing of a ladder diagram program. A partial circuit search unit searches and extracts a partial circuit corresponding to a ladder circuit of an inputted command name when the input operation unit receives the command name of the ladder circuit to be inserted into the ladder diagram program. A display unit outputs an input candidate corresponding to the partial circuit extracted by the partial circuit search unit. A replacement processing unit receives selection of the input candidate outputted from the display unit, and replaces, with the selected input candidate, the ladder circuit, the command name of which has been inputted by the input operation unit.

According to the present invention, an input operation unit receives an input related to generation and editing of a ladder diagram program. A partial circuit search unit searches and extracts a partial circuit corresponding to a ladder circuit of an inputted command name when the input operation unit receives the command name of the ladder circuit to be inserted into the ladder diagram program. A display unit outputs an input candidate corresponding to the partial circuit extracted by the partial circuit search unit. A replacement processing unit receives selection of the input candidate outputted from the display unit, and replaces, with the selected input candidate, the ladder circuit, the command name of which has been inputted by the input operation unit.