A sheet-like heater is provided that can be heated quickly and demonstrates excellent heat uniformity, with the wires of the sheet-like heater being insusceptible to breaking. The sheet-like heater has a layered structure and includes: a sheet-like base; a first resin layer that is attached to a principal face of the sheet-like base and comprises a first resin agent; a mixed layer A that is connected to the first resin layer and comprises a mixture of the first resin agent and metallic fibers; a metallic fiber layer that is connected to the mixed layer A, consists only of metallic fibers, and contains air therein; a mixed layer B that is connected to the metallic fiber layer and comprises a mixture of metallic fibers and a second resin agent; and a second resin layer that is connected to the mixed layer B and comprises the second resin agent.