A premixed combustion burner includes: a mixing part including a first peripheral wall having a center burner axis, a mixing region for mixing fuel and air in the first peripheral wall, and air supply ports arranged circumferentially and open in the first peripheral wall; a nozzle on the mixing part side, a second peripheral wall having a center burner axis, a premixed gas passage continuous to the second peripheral wall mixing region, and a cooling passage in the second peripheral wall; and a header part proximal to the mixing part, and a first header chamber with a fuel supply port, second header chamber, and fuel ejection port for communication between the second header chamber and mixing region. The first peripheral wall has an outward path connecting the first header chamber and a cooling passage inlet, and a return path connecting cooling passage outlet and the second header chamber.