There is provided a tempo detection apparatus capable of detecting, from the acoustic signal of a human performance of a musical piece having a fluctuating tempo, the average tempo of the entire piece of music and the correct beat positions, and further, the meter of the musical piece and the position of the first beat. The tempo detection apparatus includes an input section; a chromatic-note-level detection section for applying an FFT calculation to obtain the level of each chromatic note at each of predetermined timings; a beat detection section for summing up incremental values of respective levels of all the chromatic notes, indicating the degree of change of entire sound at each of the predetermined timings, and for detecting an average beat interval and the position of each beat from the total of the incremental values of the levels; and a measure detection section for calculating the average level of each chromatic note for each beat, for summing up incremental values of all the chromatic note for each beat to obtain a value indicating the degree of change, and for detecting a meter and the position of a measure line from the value indicating the degree of change of entire sound at each beat.