In this paper, a novel, wearable cardiac monitor (hereafter called WHAM) is proposed which allows a continuous and real-time monitoring of user's cardiac conditions. The proposed device is composed of 3 main components: a disposable electrode, a controller, and personal gateway (e.g., cellular phone, PDA, and smart phone etc.). The ECG signal is recorded according to the surface Laplacian of the body surface potential. We investigated the feasibility of WHAM as a wearable ambulatory device for continuously and on-line monitoring a user's cardiac conditions. To this end, the ECG signals recorded with WHAM were compared with those obtained by Wilson's unipolar chest leads, that is, v1 to v6. As a result, the ECG signals recorded with WHAM showed the similar morphology to Wilson's unipolar chest leads (v1 to v6) with the exception of P and T waves, although there is a difference between amplitudes of both signals. Also, it is shown that the R-peaks are accurately detected by the algorithm at the accuracy of more than 99% for the ECG signals of WHAM recorded during resting and walking. From these results, it is found that the WHAM shows enough feasibility and has advantages as a wearable ambulatory monitoring device in that the hardware is miniaturized enough small to integrate on a small region, thereby no wire leads need.