A modulation parameter selecting method in a system including, as a scheduler portion, a temporal coding rate determining portion that determines a coding rate temporarily, a temporal modulation rate determining portion for selecting a modulation method that satisfies required quality and has a maximum transmission rate in each channel, under the temporarily determined coding rate, and a transmission rate computing portion that calculates a transmission rate from the coding rate determined at the temporal coding rate determining portion and the modulation method in each of the channels selected at the temporal modulation method determining portion, in which processing from the temporal coding rate determining portion to the transmission rate computing portion is performed repeatedly with respect to selectable coding rates and a coding rate with a maximum transmission rate and a modulation method in each of the channels are determined.