An electric toothbrush wherein the number of revolution of a motor shaft is in match with the frequency of reciprocating motion of the brush. A motor (2) housed in a tubular case (1) is coupled to a reciprocating shaft (5) slidably extending through the forward end of the case by a scotch yoke mechanism (40) for converting one turn of rotation of the motor shaft (21) into one stroke of reciprocating pivotal movement of a pivotal body (4), and by motion conversion means (3) for converting one stroke of reciprocating movement of the pivotal body (4) into one stroke of linear reciprocating motion of the reciprocating shaft (5).