Engine control device for work vehicle

An engine control device for a work vehicle includes: a hydraulic pump 2 driven by an engine 1; a hydraulic actuator 5 driven with pressure oil supplied from the hydraulic pump 2; a drive disallowing means 3 for disallowing drive of the hydraulic actuator with the pressure oil supplied from the hydraulic pump 2; a disallowed drive detection means 14 for detecting whether or not the drive disallowing means 3 is disallowing the drive; and a rotation rate control means 12 16 for executing control so as to adjust an engine speed to a low rotation rate NS, lower than a minimum rotation rate (hereafter referred to as a low idle rotation rate NL) at which the hydraulic actuator 5 can still be driven, at least when the disallowed drive detection means 14 detects that the drive disallowing means 3 is disallowing the drive.