A portable electrocardiograph (100A) includes a housing (101) having an almost rectangular parallelepiped shape, a negative electrode (110) provided for a grip part (160) positioned adjacent to an end in the longitudinal direction of the housing (101), and a positive electrode (120) provided on a left side face (107) positioned at the other end in the longitudinal direction of the housing (101). The user measures electrocardiographic waves by holding the grip part (160) by his/her right hand and pressing the left side face (107) against the body. The left side face (107), which is an electrode formation face of the positive electrode (120), includes an electrode region (a contact face (121) with the body) on which the positive electrode (120) is positioned and a non-electrode region (flat face (107a)) which is positioned so as to surround the electrode region and formed to be flat.
