To provide a control device for a diesel engine, which can quickly suspend its operation.

This diesel engine equipped with a distribution type fuel injection pump, is provided with a required fuel injection quantity computing part 31 capable of referring to the quantity Q of required fuel infection in response to engine revolutions H and the opening TVO of an accelerator based on an operation map, a fuel injection quantity computing part 32 for suspending an engine operation, which refers to the required fuel injection quantity Q in response to engine revolutions based on an engine suspension map, and with a map change-over means 33 making the change-over of a map in response to the ON/OFF of an ignition switch. And a control sleeve is so constituted as to be moved to a position accelerating the suspension of an engine operation when a condition of operation suspension is accomplished.