A radio communication apparatus includes a discrete Fourier transformer that performs a frequency-domain transform on each of a plurality of reception signals received at a plurality of receiver chains and generates a plurality of frequency-domain signals, a covariance matrix calculator that calculates covariance of the plurality of frequency-domain signals, a deviation calculator that calculates a cumulative value of covariance in a first frequency range and a second frequency range and calculates deviation of the covariance in the plurality of frequency ranges, and an adjacent-channel interference determiner that determines presence or absence of adjacent-channel interference using the cumulative value of the covariance.