A portable negative ion electric toothbrush is provided. A portable negative ion electric toothbrush includes a main body in which a chamber is formed and a through hole is formed through a side wall that defines the chamber, a circuit board provided in the chamber, and an outer periphery of the main body. A handle 4 that covers the through-hole and is provided with a seal structure 5 that covers and seals the through-hole. The seal structure includes a conductive adhesive and the main body. A groove recessed from the outer peripheral surface of the handle toward the chamber, the conductive adhesive is housed in the groove and the through hole, and the inner peripheral surface of the handle is pressed against the conductive adhesive, and the handle and Since the conductive adhesive has conductivity, the handle and the circuit board are electrically connected. [Selection] Figure 2【課題】携帯式マイナスイオン電動歯ブラシを提供する。【解決手段】携帯式マイナスイオン電動歯ブラシは、チャンバーが形成され、前記チャンバーを画定する側壁を貫通する貫通穴が開設された本体と、前記チャンバー内に設けられた回路基板と、前記本体の外周に外挿され、前記貫通穴を覆うハンドル４と、を備え、前記貫通穴には前記貫通穴を覆って密封するシール構造５が設けられ、前記シール構造が、導電性接着剤と、前記本体の外周面から前記チャンバーに向かって凹む溝とを備え、前記導電性接着剤が前記溝及び前記貫通穴に収容され、前記ハンドルの内周面が前記導電性接着剤に押し付けられ、前記ハンドル及び前記導電性接着剤が何れも導電性を有することで、前記ハンドルと前記回路基板とが電気的に接続される。【選択図】図２
