A plate spring bogie (1) includes: a cross beam (4) configured to support a carbody (11) of a railcar; a pair of front and rear axles (5) sandwiching the cross beam (4) and respectively arranged in front of and behind the cross beam in a railcar longitudinal direction so as to extend in a railcar width direction; bearings (7) respectively provided at both railcar width direction sides of each of the axles (5) and configured to rotatably support the axles (5); axle boxes (8) configured to respectively accommodate the bearings (7); plate springs (30) extending in the railcar longitudinal direction so as to respectively support both railcar width direction end portions (4a) of the cross beam (4) and each including both railcar longitudinal direction end portions (30c) respectively supported by the axle boxes (8); and an auxiliary supporting mechanism (50) configured to support the railcar width direction end portion (4a) of the cross beam (4) in a case where the railcar width direction end portion (4a) of the cross beam (4) is displaced downward beyond a predetermined elastic deformation range of the plate spring (30).