An electrocardiographic electrode is disclosed, which comprises an electrode element consisting of a synthetic resin electrode element having a head portion with a lead attached thereto and having a straight recessed portion, a neck portion having an engagement portion narrower than the head portion and capable of being engaged in an expansible member and a straight portion continuous to the straight recessed portion of the head portion and a bottom portion formed under, broader than and supporting the neck portion and to be held in contact with the skin of a living body, the outer surface of the synthetic resin electrode element member being imparted with electric conductivity by coated metal powder, an expansible member engagedly locked in the engagement portion of the neck portion, and an adhesive film consisting of an adhesive, having a central portion and secured to the expansible member to be held in close contact with the skin of the living body.