To provide an electric toothbrush having a high usability for an operator, allowing the operator to secure a sufficient operative field, and exchanging a brush at low cost.

This electric toothbrush 30 is provided with a trunk part 33 gripped by a user, a case body 32 consisting of a brush support part 51 to be connected to the trunk part 33, a cup-shaped toothbrush 65 supported to the tip of the brush support part and a driving mechanism 36 reciprocatingly rotating the cup-shaped toothbrush 65. The cup-shaped toothbrush 65 is formed with a water supply opening part 71 at its central part, and the brush support part 51 is formed with suction opening parts in the periphery of the cup-shaped toothbrush 65. The case part 32, in its inside, is disposed with inner water supply pipes 44 and 45 and inner drains 46 and 47.