To provide a thermal insulating sheet, a sheet for use in a truck bed, and a thermal insulating case having superior easiness to handle while having a high thermal insulation ability. A thermal insulating sheet 1 comprises a laminated member comprising a tarpaulin sheet 10, a plurality of synthetic resin nonwoven fabric sheets 11a, 11b, and polyester canvas 12, with the plurality of synthetic resin nonwoven fabric sheets 11a and 11b being provided between the tarpaulin sheet 10 and the polyester canvas 12. A perimeter the laminated member possesses at least a part where at least the tarpaulin sheet and the polyester canvas are fuse-bonded, and remaining parts where the laminated member is stitched together. The polyester canvas possesses one or more through holes, through which air can enter into and exit out of the laminated member, whereas the tarpaulin sheet does not possess any through holes.
