A plate spring bogie includes: a cross beam supporting a carbody of a railcar; a pair of front and rear axles sandwiching and respectively arranged in front of and behind the cross beam in a railcar longitudinal direction to extend in a railcar width direction; bearings respectively provided at both railcar width direction sides of each of the axles and rotatably supporting the axles; axle boxes respectively accommodating the bearings; plate springs extending in the railcar longitudinal direction to respectively support both railcar width direction end portions of the cross beam and each including both railcar longitudinal direction end portions respectively supported by the axle boxes; and an auxiliary supporting mechanism supporting the railcar width direction end portion of the cross beam in a case where the railcar width direction end portion of the cross beam is displaced downward beyond a predetermined elastic deformation range of the plate spring.