Provided is a programmable controller capable of simplifying handshake processing between control devices. The programmable controller, which performs the handshake processing in conjunction with a reception-side device, is provided with an output signal area in which a signal to be output to the reception-side device is held, an input signal area in which a signal output by the reception-side device is held, a sequential program execution part configured to execute a sequential program, an output signal temporary area in which an output signal from the sequential program is held, and a handshake processing part configured to copy a signal state of the output signal temporary area in the output signal area and hold the signal state of the output signal area so that the input signal area is notified of a completion signal.