A vaporizer has gas passage formed inside of main body of a dispersion part, a gas inlet opening to introduce pressurized carrier gas into gas passage, a part to supply raw materials solution to carrier gas passing gas passage, a gas outlet to send carrier gas including dispersed raw material solution to vaporization part, a dispersion part to flow through gas passage having a part to cool, a vaporization pipe connected with a reaction part and gas outlet of dispersion part of the device, and a heater to heat vaporization pipe is provided, a vaporization part to heat and vaporizes the carrier gas where raw materials solution is dispersed is provided, and a radiation prevention portion having small hole for the outside of gas outlet is provided.