Heating floor panel unit and floor structure of railcar

A heating floor panel unit of a railcar includes: a heater-equipped floor panel; a first flange horizontally projecting from one end of the floor panel in a car longitudinal direction and fixed to a carbody by a fastening member; and a second flange horizontally projecting from the other end of the floor panel in the car longitudinal direction and fixed to the carbody by a fastening member. The first flange and the second flange are located at such a height that upper ends of the fastening members are located below an upper surface of the heater-equipped floor panel. The first flange, as viewed from above, is located in such a manner that a position of the first flange in a direction orthogonal to a direction in which the first flange projects does not overlap a position of the second flange in the orthogonal direction.