A wireless communication apparatus of the invention has a determination section that determines which one of a plurality of formats is used for determining transmission symbols to be transmitted to another communication apparatus; a control section that determines a type a sequence length of an orthogonal code and used for assigning ACK/NACK symbols to identical symbols in an identical slot on basis of the format determined by the determination section, without depending on a number of transmission symbols capable of being transmitted to the other communication apparatus; a spreading section that spreads the ACK/NACK symbols by an identical type of orthogonal code in the plurality of formats set based on the type and the sequence length of the orthogonal code determined by the control section; and a transmission section that transmits the spread ACK/NACK symbols using the determined format.