A work processing apparatus, comprising: a vaporizer having: a vaporization part for vaporizing a vaporization target liquid, the vaporization target liquid being a carboxylic acid; and a heat supplier for supplying heat to the vaporization part; a chamber for processing a work therein, the chamber being configured to be able to be airtight from outside, where a flow path in the vaporizer through which the vaporization target liquid flows and an inside of the chamber are communicated with each other; and a vacuum pump for creating a negative pressure in the inside of the chamber and an inside of the flow path through which the vaporization target liquid flows; characterized in that the vaporization part includes a heat storage body having a heat capacity higher than that of a vaporization target liquid by a predetermined ratio, wherein the heat storage body has a heat storage body flow path formed therein, the heat storage body flow path being a flow path through which the vaporization target liquid flows; and wherein the predetermined ratio is a ratio of heat capacity at which a temperature drop of the heat storage body by heat transfer from the heat storage body to a planned amount of the vaporization target liquid intermittently flowing through the heat storage body flow path is within a predetermined range, wherein an amount of heat transferred from the heat storage body to the vaporization target liquid is an amount of heat necessary to vaporize the vaporization target liquid at a planned proportion, and wherein the planned amount of the vaporization target liquid is an amount used in single processing of the work in the chamber. a vaporizer having: a vaporization part for vaporizing a vaporization target liquid, the vaporization target liquid being a carboxylic acid; and a heat supplier for supplying heat to the vaporization part; a vaporization part for vaporizing a vaporization target liquid, the vaporization target liquid being a carboxylic acid; and a heat supplier for supplying heat to the vaporization part; a chamber for processing a work therein, the chamber being configured to be able to be airtight from outside, where a flow path in the vaporizer through which the vaporization target liquid flows and an inside of the chamber are communicated with each other; and a vacuum pump for creating a negative pressure in the inside of the chamber and an inside of the flow path through which the vaporization target liquid flows; characterized in that the vaporization part includes a heat storage body having a heat capacity higher than that of a vaporization target liquid by a predetermined ratio, wherein the heat storage body has a heat storage body flow path formed therein, the heat storage body flow path being a flow path through which the vaporization target liquid flows; and wherein the predetermined ratio is a ratio of heat capacity at which a temperature drop of the heat storage body by heat transfer from the heat storage body to a planned amount of the vaporization target liquid intermittently flowing through the heat storage body flow path is within a predetermined range, wherein an amount of heat transferred from the heat storage body to the vaporization target liquid is an amount of heat necessary to vaporize the vaporization target liquid at a planned proportion, and wherein the planned amount of the vaporization target liquid is an amount used in single processing of the work in the chamber.