A base station apparatus is used in a mobile communication system that uses an OFDM scheme in a downlink. The base station apparatus includes: a unit configured to perform inverse Fourier transform on a signal in which a first signal and a second signal is mapped to subcarriers with different transmission power density, and to generate a transmission signal; and a transmission unit configured to transmit the transmission signal to a user apparatus. A subcarrier (prohibited subcarrier) in which mapping of the second signal is prohibited is determined such that transmission power density of the second signal is kept constant among a plurality of OFDM symbols regardless of whether the first signal is included in an OFDM symbol including the second signal. The prohibited subcarrier is determined based on a subcarrier to which the first signal is mapped.