To provide an electric rotary pestle which can grind grains by the pestle rotating by itself.

The invention is composed of a gripping bar section of approximately the same appearance as a normal pestle in shape and size and a rotary head section. A rotary shaft of the gripping bar which contains a speed-adjustable motor is fitted into a concave section of the rotary head section in a detachable manner. The rotary head section is rotationaly driven by the rotation of the rotary shaft of the speed-adjustable motor of the gripping bar to grind grains inside a mortar extremely easily regardless of the skill or how good or bad the user is.