Disclosed is a hollow molded article which has an opening portion communicating with a flow channel and which can be manufactured simply. The hollow molded article includes a panel and flow channels. The panel includes a first resin sheet and a second resin sheet partly welded with the first resin sheet. The flow channels are disposed between the first resin sheet and the second resin sheet, and include connection portions for external connection which are disposed on a peripheral edge of the panel. The connection portions are formed by the first resin sheet and the second resin sheet.