An ignition device for engine according to the present invention performs continuous spark discharge of an ignition plug by using a multiplex signal, an integration signal or a control signal. In the multiplex signal, discharge continuous signals IGW#1 to 4 for cylinders of the engine have been multiplexed. In the integration signal, a discharge continuous signal IGW and a secondary current instruction signal IGA have been added to an ignition signal IGT. In the control signal, the secondary current instruction signal IGA has been added into the multiplex signal or the integration signal. This structure can reduce the total number of signal lines connected between an ECU and a controller, and further reduce a signal line to transmit the secondary current instruction signal IGA.