Abstract: An automatic interdental cleaner for cleaning between teeth more effectively and cleanly without hurting the gum between the teeth is disclosed. The cleaner comprises: a grip portion disposed therein with a battery and a motor and a power switch at one wall side; a power transmitting unit coupled to one end of the grip portion for supplying power from the grip portion and formed with a first insertion hole at a free end; an interdental brush portion including a brush holder having a shape corresponding to that of the first insertion hole of the power transmitting unit and also having one end insertedly fixed to the first insertion hole, and a brush fixed to the other end of the brush holder; and an adapter portion one end of which is coupled to the power transmitting unit and the other end of which accepts the interdental brush portion, such that spaces between the teeth can be automatically cleaned using the automatic interdental cleaner.