A knocking control device having a knocking detecting circuit for detecting, as an electrical signal, an amount of variation corresponding to an internal pressure variation within a cylinder of an engine due to an engine knocking; an averaging circuit for converting the electrical signal from the knocking detecting circuit to a signal corresponding to a knocking energy; a crank angle detecting circuit for detecting a rotation phase of the engine; a comparison circuit for comparing the output signal corresponding to the knocking energy of the averaging circuit with a reference value defining a knocking allowable level to obtain a control signal for maintaining an engine knocking strength in a predetermined range; and an ignition control circuit connected to an ignition circuit, for controlling the ignition timing of the ignition circuit by the control signal from the comparison circuit. The present invention can detect the knocking strength with high accuracy as an electrical signal based on the cylinder internal pressure variation due to knocking and can carry out a knocking strength control suitable for characteristics of an engine by using the electrical signal. Also the present invention can remarkably improve an engine combustion efficiency and fuel consumption percentage by accepting a knocking to some extent.