Abstract: A continuous flow type heating apparatus using microwave, which can continuously supply hot water with practically usable flow amount and temperature. An open part is formed on a top face of a horizontally prolonged empty box 10 to become an emitting port of the microwave. The empty box 10 is divided into two by a vertical partition except for the upper and lower part of the emitting port. One side of the space is horizontally divided into three by two of an upper and a lower partitions 12, 13 on which slits 12a, 13a are set at a desired interval. The space formed on the partition 12 becomes a first irradiation part 4. The space formed under the partition 13 and connected in lower part to the space on another side becomes a second irradiation part 5. A water supply pipe 2 is disposed at the center of the space formed between the partitions 12 and 13. The microwave from a microwave oscillator 6 is irradiated from the emitting port into the empty box 10.