Provided is an engine control device which can suppress a shortage of output terminals of the control unit and an increase of costs even in a multiple-cylinder internal combustion engine equipped with ignition energy supply units of two systems. An engine control device controls a multiple-cylinder engine in which ignition energy supply units of two systems are provided for every cylinder. A signal is transmitted through a common signal line to a plurality of ignition energy supply units of one system among the ignition energy supply units of the two systems to control the ignition energy supply units of the one system.