An electromagnet driving circuit particularly suited for use in impact printers as a means for driving to move a printing hammer includes a current control circuit for controlling a driving current to be applied to an electromagnet. In one aspect of the invention, a feed back circuit is provided between a voltage source and the current control circuit so as to compensate for fluctuations at the voltage source. In another aspect of the invention, the current control circuit is structured to use a temperature-dependent reference voltage in determining the level of the driving current thereby allowing to carry out a temperature-compensated operation.