Abstract: A heater for piping includes a plurality of shells connected via hinges. The shells are adapted to be mounted on an outer circumferential wall of piping having a circular cross section to enclose the piping and form a polyhedron along the piping. Thermal insulators are disposed over entire surfaces of inner walls of the shells. A plurality of molds are disposed at the inner walls and are adapted to abut on the outer circumferential wall of the piping in the mounted state. A plurality of heating elements are disposed at the inner walls of the shells so that the heating elements are positioned in a space formed between corners of the polyhedron and the outer circumferential wall of the piping and extend in the longitudinal direction of the piping in the mounted state.