A portable electrocardiograph, characterized in that a clamping cover which tends to close automatically is provided on one end of a housing; a finger hole is provided between the clamping cover and the housing; a lower half of the inner wall of the finger hole is defined on the housing; an upper half of the inner wall of the finger hole is provided on the clamping cover; the lower half of the inner wall is provided with a first electrode; the other end of the housing is provided with a second electrode; and the back face of the housing is provided with a third electrode, in which the first electrode or the third electrode is a neutral electrode. According to the present invention, at least one portion of at least one of the middle finger, the so-called ring finger, and the little finger of the user's hand for grasping the electrocardiograph can contact the neutral electrode, such that the error of the measured result caused by electrical potential fluctuation on the measured person's body can be eliminated.