A signal processing apparatus includes an absolute value unit configured to convert an audio signal into absolute values, a representative value calculation unit configured to calculate representative values of consecutive sample values included in blocks of the audio signal which has been converted into the absolute values using at least maximum sample values among values of the samples included in the blocks for individual blocks, an average value calculation unit configured to determine a section which includes a predetermined number of consecutive blocks as a frame and calculate a maximum value of the representative values of the blocks included in the frame and an average value of the representative values of the blocks included in the frame, and a detector configured to detect click noise in the frame on the basis of a ratio of the maximum value to the average value.