An electric coffee grinder in the invention has a body, a holding seat, a motor seat, a fixing seat, a base, a receiving basket, a feeding basket and an upper cover. The electric coffee grinder can be supplied electricity by batteries press button of the body is depressed by a user, a button switch will be actuated by the press button to form an open electric circuit to start a motor to rotate a reducing gear assembly to turn a journal to swivel a spindle to turn a grinding member, thereby enabling the electric coffee grinder of the invention to proceed with grinding movements, which is quick in grinding, compact in dimension and convenient in operation.