A base station device comprising: a determining unit that determines a combination of a plurality of users having different reception qualities; a first calculating unit that calculates a throughput obtained when a modulation scheme is allocated to each of the plurality of users in dependence upon the reception quality of the respective user; a second calculating unit that calculates a throughput obtained when a hierarchical modulation channel is allocated to each of the plurality of users in dependence upon the respective reception quality of the user, wherein the hierarchical modulation channels are obtained by hierarchizing bits transmitted by a modulation symbol into levels based upon a likelihood of an error to occur using the bit, bits in each level being a hierarchical modulation channel for allocation to a user; an allocating unit that generates, when the throughput calculated by the second calculating unit is equal to or greater than the throughput calculated by the first calculating unit, a plurality of the hierarchical modulation channels, and allocates the hierarchical modulation channels to the respective users such that the hierarchical modulation channel having the bits with the smallest likelihood of error is allocated to the user having the lowest reception quality among the users in the combination, and the hierarchical modulation channel having the bits with the greatest likelihood of error is allocated to the user having the highest reception quality among the users in the combination; a mapping unit that maps data for each user to the hierarchical modulation channel allocated to each user by the allocating unit; and a transmitting unit that transmits the data mapped by the mapping unit. a determining unit that determines a combination of a plurality of users having different reception qualities; a first calculating unit that calculates a throughput obtained when a modulation scheme is allocated to each of the plurality of users in dependence upon the reception quality of the respective user; a second calculating unit that calculates a throughput obtained when a hierarchical modulation channel is allocated to each of the plurality of users in dependence upon the respective reception quality of the user, wherein the hierarchical modulation channels are obtained by hierarchizing bits transmitted by a modulation symbol into levels based upon a likelihood of an error to occur using the bit, bits in each level being a hierarchical modulation channel for allocation to a user; an allocating unit that generates, when the throughput calculated by the second calculating unit is equal to or greater than the throughput calculated by the first calculating unit, a plurality of the hierarchical modulation channels, and allocates the hierarchical modulation channels to the respective users such that the hierarchical modulation channel having the bits with the smallest likelihood of error is allocated to the user having the lowest reception quality among the users in the combination, and the hierarchical modulation channel having the bits with the greatest likelihood of error is allocated to the user having the highest reception quality among the users in the combination; a mapping unit that maps data for each user to the hierarchical modulation channel allocated to each user by the allocating unit; and a transmitting unit that transmits the data mapped by the mapping unit.