An index calculating unit calculates a tonality index of a signal component of each area of an input signal transformed into a time frequency domain based on intensity (for example, power spectrum) of the signal component and a function (quadratic function) obtained by approximating the intensity of the signal component. A music determining unit determines whether or not each area of the input signal includes music based on the tonality index. The present technology can be applied to a music section detecting apparatus that detects a music part from an input signal in which music is mixed with noise.