The present invention relates to a low-frequency stimulator using music, and a weight-loss assisting system having a low-frequency stimulator. The low-frequency stimulator according to an embodiment of the present invention includes: a beat extracting unit extracting a beat through a sound pressure magnitude comparison between one or more acoustic signals having different frequencies generated when music is played on a music player; a pulse generator generating a pulse having the same magnitude and that of the extracted heat; and a pair of electrode pads attached to a user's body and applying an electric stimulus having an intensity corresponding to the magnitude of the generated pulse to the user's body.