An engine control device is provided including: detection units for detecting a driving state of a work machine using a generator, target engine speed setting units for causing, on the basis of the driving state, a target engine speed set for a case where electric power generation by the generator is OFF to be the same as a target engine speed set for a case where the electric power generation by the generator is ON, and engine target output calculation units for calculating an engine target output during electric power generation OFF that can be output at most when the electric power generation by the generator is OFF, and calculates an engine target output obtained by adding an output corresponding to an electric power generation amount by the generator to the engine target output when the electric power generation by the generator is ON.