A method and device for detecting music parts within a content at relatively low cost of arithmetic operations. The device includes a first power calculating section for calculating a sum of powers of respective channels of two-channel sound, a second power calculating section for calculating a difference between the powers of the respective channels of the two-channel sound, a power ratio calculating section for calculating a ratio between the powers calculated by the first and second power calculating sections, a comparing section for comparing the ratio calculated by the power ratio calculating section with a prescribed threshold value, and a determination section for performing determination of a music segment based on a result of comparison by the comparing section.