Heater and its production method

In the parallel heater in which the heater pattern is formed in parallel between the terminals, it is possible to easily perform resistance adjustment before productization without being skilled, and the original function is not impaired. In the heater (30) in which the heater patterns (31, 32) are provided in parallel between the terminals (A, B), each terminal is divided into two parts, that is, divided terminals that are only electrically connected to the heater pattern (31) ( 37) and a split terminal (38) that is only turned on with the heater pattern (32). The dummy series path (45) formed between the divided terminals (37, 37) and the divided terminals (38, 38) are formed in a state before the heater body (36) is fabricated and before the power supply bolts (50) are mounted. After the virtual series path (46) is respectively adjusted by the resistors, a plurality of virtual series heater patterns are turned on by installing power supply bolts to the respective terminals to form a parallel circuit.