Heating unit of vehicle heating system

A heating unit (7) of a vehicle heating system arranged in a blown air flow path for either internal air or external air to be blown into the inside of a vehicle in order to heat blown air includes a casing (15) made of a metal material capable of electromagnetically shielding microwaves and arranged in the blown air flow path, a support (21) arranged in the hollow section of the casing, a large number of microwave absorbing/heat emitting members (23) arranged at the support at appropriate intervals, each having a hollow section with an upstream side opening and a downstream side opening at the opposite ends of the support and a microwave outputting means (25,27) arranged in the casing to output microwaves.