A heat supply system is provided which enables use of small pipes with the same diameter for both feed branch pipes and return branch pipes, thus reducing the initial cost and also suppressing heat emission loss. The heat supply system comprises a heat exchanger 1, a feed main pipe 2, a return main pipe 3, a feed branch pipe 4 connected to the feed main pipe 2, a first return branch pipe 5 for directing the flow of a heat medium to an edge section in the downstream side of the feed branch pipe 4, a plurality of load pipes connected in parallel to a section between the feed branch pipe 4 and the first return branch pipe 5 each having a load member 7 provided thereon, and a second return branch pipe 6 connected to a section between an edge section in the downstream side of the first return branch pipe 5 and the return main pipe 3, said heat supply system having a plurality of branch pipe paths 11 including therein the feed branch pipe 4, first return branch pipe 5, load pipe 8, and second branch pipe 6.