In an engine which may show a behavior where an engine speed is not always minimized after compression top dead center of a cylinder in which poor fuel injection occurred, the cylinder in which poor fuel injection occurred is detected. A common rail diesel engine (1) includes a individual reference number-of-revolutions output unit (30) for outputting the individual reference number of revolutions Nstdi of each cylinder corresponding to each injector (3) incident to fuel injection thereof, an engine speed sensor (6) for calculating the individual actual number of revolutions Ni of each cylinder corresponding to each injector (3) incident to fuel injection thereof, and fuel injection failure detection means for judging a cylinder temporarily judged as poor fuel injection as a cylinder of poor fuel injection when the plus and minus by a contrast arithmetic operation unit (80) coincide entirely in each cylinder and the absolute value |ΔNi′| of the difference in number of revolutions at the time of forced stop means is entirely above the absolute value |ΔNi| of the difference in the number of revolutions at the time of temporary judgment means.