the present invention relates to a portable boiler for a hot mat , which comprises : a water reservoir , one side of which has an inlet pipe for introducing water circulating through the hot mat , and which stores the water ; a heat transfer unit in which the water discharged from the water reservoir flows along a flow channel pipe to be heat exchanged , wherein the water is discharged to the hot mat via an outlet pipe formed at one side thereof ; a heating unit which burns the fuel gas fed from a fuel tank to heat the water in the heat transfer unit ; and a housing which forms the outer appearance of the boiler .