A beat detection device includes: a pulse wave sensor adapted to detect and output a pulse wave signal; a body motion sensor adapted to detect and output a body motion signal due to a body motion of a human body; a pulse wave signal filtering section adapted to generate an adaptive filter based on the body motion signal to extract a noise signal in the pulse wave signal, and to output a beat signal obtained by eliminating the noise signal from the pulse wave signal; and a filter coefficient setting section adapted to set a coefficient of the adaptive filter to be a predetermined value in response to detection of increase in a body motion change beyond a predetermined threshold value based on the body motion signal.