This invention provides an improved circuit of 1394b signal transmission line including a 1394b signal transmission drive circuit, a load circuit, a first signal line, a second signal line and a 1394b interface characterizing in including a first impedance, a second impedance and a third impedance, in which, the second impedance is serial between the interface and the first signal line, the third impedance is serial between the interface and the second signal line, one end of the first impedance is connected between the first signal line and the second impedance and the other end is between the second signal line and the third impedance. |