A wireless communications apparatus according to the present invention includes a scheduler which allocates, to a user apparatus, at least one resource block included in a system bandwidth; an interleaver which rearranges an order of bits within a bit sequence according to a specified pattern; a unit which creates a transmit symbol including the interleaved bit sequence; and an interleaving-pattern determining unit which determines a range of the bit sequence to be rearranged based on a number of the resource blocks, a data modulation scheme, and a channel encoding rate, determines a rearranging pattern according to the range, and communicates the determined pattern to the interleaver.