This paper describes a basic method to estimate satellite-transmitting power to compensate for rain attenuation by an advanced broadcast satellite system in which a beam steering antenna is employed for rain attenuation compensation. A method to estimate the mode of peak rain attenuation in a certain 10-minute-rainfall is proposed in this paper. Satellite-transmitting power needed to compensate for rain attenuation by use of 10-minute-rainfall data collected from about 1300 points in Japan is estimated. As a result, it is shown that an additional satellite transmitting power of about 1000 W with plural boosted beams, which are about 100km in diameter, might be able to compensate for most of rain attenuation events on Ku band in Japan.