An apparatus for sterilizing aqueous solution using a flexible ultraviolet irradiator, comprising: an aqueous solution flow tube formed in a helical shape, configured to block exposure of ultraviolet rays from an inside of the aqueous solution flow tube to an outside thereof, and through which aqueous solution flows; and an ultraviolet irradiator formed of a flexible material insertable inside the aqueous solution flow tube and configured to irradiate the aqueous solution with the ultraviolet rays to sterilize the aqueous solution, wherein the aqueous solution flow tube includes: an inlet portion configured to enable the aqueous solution to flow in; an outlet portion configured to enable the aqueous solution to flow out; a reaction portion formed in the helical shape between the inlet portion and the outlet portion and at which the aqueous solution is sterilized by the irradiation of the ultraviolet rays; and valves (16, 17) respectively provided between the inlet portion and the reaction portion and between the outlet portion and the reaction portion, and configured to control a flow of the aqueous solution, wherein the ultraviolet irradiator includes: a plurality of ultraviolet light emitting diodes, LEDs, configured to irradiate the aqueous solution with the ultraviolet rays; and a flexible substrate connected to the plurality of ultraviolet LEDs to supply electric power thereto, inserted inside the reaction portion, and having one end formed in an annular shape, and wherein the reaction portion includes: a fixing portion formed at a part in contiguity with the inlet portion and coupled to the annular shape to fix one end of the flexible substrate; and a through hole formed at a part in contiguity with the outlet portion and configured to pass through and connect the other end of the flexible substrate to an external electric power source. an aqueous solution flow tube formed in a helical shape, configured to block exposure of ultraviolet rays from an inside of the aqueous solution flow tube to an outside thereof, and through which aqueous solution flows; and an ultraviolet irradiator formed of a flexible material insertable inside the aqueous solution flow tube and configured to irradiate the aqueous solution with the ultraviolet rays to sterilize the aqueous solution, wherein the aqueous solution flow tube includes: an inlet portion configured to enable the aqueous solution to flow in; an outlet portion configured to enable the aqueous solution to flow out; a reaction portion formed in the helical shape between the inlet portion and the outlet portion and at which the aqueous solution is sterilized by the irradiation of the ultraviolet rays; and valves (16, 17) respectively provided between the inlet portion and the reaction portion and between the outlet portion and the reaction portion, and configured to control a flow of the aqueous solution, an inlet portion configured to enable the aqueous solution to flow in; an outlet portion configured to enable the aqueous solution to flow out; a reaction portion formed in the helical shape between the inlet portion and the outlet portion and at which the aqueous solution is sterilized by the irradiation of the ultraviolet rays; and valves (16, 17) respectively provided between the inlet portion and the reaction portion and between the outlet portion and the reaction portion, and configured to control a flow of the aqueous solution, wherein the ultraviolet irradiator includes: a plurality of ultraviolet light emitting diodes, LEDs, configured to irradiate the aqueous solution with the ultraviolet rays; and a flexible substrate connected to the plurality of ultraviolet LEDs to supply electric power thereto, inserted inside the reaction portion, and having one end formed in an annular shape, and a plurality of ultraviolet light emitting diodes, LEDs, configured to irradiate the aqueous solution with the ultraviolet rays; and a flexible substrate connected to the plurality of ultraviolet LEDs to supply electric power thereto, inserted inside the reaction portion, and having one end formed in an annular shape, and wherein the reaction portion includes: a fixing portion formed at a part in contiguity with the inlet portion and coupled to the annular shape to fix one end of the flexible substrate; and a through hole formed at a part in contiguity with the outlet portion and configured to pass through and connect the other end of the flexible substrate to an external electric power source. a fixing portion formed at a part in contiguity with the inlet portion and coupled to the annular shape to fix one end of the flexible substrate; and a through hole formed at a part in contiguity with the outlet portion and configured to pass through and connect the other end of the flexible substrate to an external electric power source.