A work comfort evaluating device is a device for evaluating a level of comfort of work by measuring myoelectric potentials of plural muscles when the work is done by antagonistic activities of the muscles. The device has a pair of detecting sensors, an amplifier, a signal processing part, a work-load intensity calculating part, and an evaluation part. The sensors sense myoelectric potentials of the muscles at a time of the work. The signal processing part calculates a synchronous contraction intensity of the muscles by using myoelectric potential waveforms. The work-load intensity calculating part calculates a level of a work load intensity in the work. The evaluation part evaluates a level of comfort of the work by normalizing the synchronous contraction intensity by the level of the work load intensity calculated.