A temperature sensor unit-equipped axle box device of a railcar bogie includes: an axle box accommodating a bearing supporting an axle; a temperature sensor unit attached to the axle box and configured to detect a temperature of an outer ring of the bearing; and an elastic body configured to bias the temperature sensor unit in such a direction that the temperature sensor unit is pressed against the outer ring. The elastic body is elastically deformable so as to follow displacement of the temperature sensor unit around a rotation axis of the bearing.