A system for supplying hydrogen using waste heat of a fuel cell includes: a fuel cell to produce electric power using hydrogen; an internal cooling line in which a cooling medium flows and configured to pass through the fuel cell while cooling the fuel cell with the cooling medium; a solid hydrogen storage provided on a downstream side of the fuel cell on the internal cooling line and configured to discharge the hydrogen through absorption of waste heat of the heated cooling medium and to supply the discharged hydrogen to the fuel cell; and a hydrogen supply line to connect the solid hydrogen storage and the fuel cell and to supply the discharged hydrogen. In particular, the internal cooling line is reconnected to the fuel cell after passing through the solid hydrogen storage and provides the cooled cooling medium to the fuel cell.