A processor of a fluctuation detection device that detects fluctuation of a body of a user, is configured to measure a first distance that is a distance to a still object existing in a first direction and a second distance that is a distance to a still object existing in a second direction different from the first direction, to calculate a first fluctuation amount that is a changing amount of the first distance and a second fluctuation amount that is a changing amount of the second distance, and to remove a changing amount of the first distance caused by breathing of the user from the first fluctuation amount and to remove a changing amount of the second distance caused by the breathing from the second fluctuation amount.
