<p>Provided is a floor structure of a railcar in which thickness of a heat insulating material can be reduced while having predetermined heat resistance. The floor structure of the railcar includes a underframe (1) having a pair of side sills (2) extending in a railcar longitudinal direction and a cross beam (3) arranged between the side sills (2) and extending in a railcar width direction, a structural floor (4) provided on an upper surface of the underframe (1), and a first heat insulating material (42a) arranged on a lower side of the structural floor (4) via an air layer (41a) for the structural floor (4).</p>
