A thermoelectric generator system according to the present disclosure includes first and second thermoelectric generator units, each including tubular thermoelectric generators. Each of the generators has a flow path defined by its inner peripheral surface, and generates electromotive force in an axial direction thereof based on a temperature difference between its inner and outer peripheral surfaces. Each unit further includes: a container housing the generators inside; and electrically conductive members providing electrical interconnection for the generators. The container has fluid inlet and outlet ports through which a fluid flows inside, and openings into which the generators are inserted. A buffer vessel is arranged between the first and second units, and has a first opening communicating with the flow paths of the generators in the first unit and a second opening communicating with the flow paths of the generators in the second unit.