A method of producing a double-sided adhesive tape, the double-sided adhesive tape including a polyethylene foam substrate and acrylic-based adhesive layers formed on respective sides thereof, the method comprising the following steps (a) to (e): Step (a) a step of irradiating a solvent-free photopolymerizable monomer composition containing an acrylic-based monomer and a photopolymerization initiator with ultraviolet rays to produce an acrylic-based polymer A having a weight average molecular weight of 700,000 to 3,000,000, preferably 750,000 to 1,000,000, by photopolymerization of the acrylic-based monomer in the absence of a cross-linking agent, whereby a polymer syrup containing the acrylic-based polymer A and an unreacted portion of the acrylic-based monomer is prepared, wherein ultraviolet irradiation conditions in the step (a) are such that ultraviolet irradiation is performed with rays at a wavelength of 250 to 400 nm applied at a power of 15 to 100 mW/cm 2 for 10 to 60 seconds in an inert gas atmosphere at a polymerization start temperature of 25 to 130°C, and is repeated 5 to 20 times at idling intervals of 20 to 40 seconds; Step (b) a step of mixing an adhesion-imparting polymer having a weight average molecular weight of 2,000 to 10,000 with the polymer syrup to prepare an adhesive coating solution; Step (c) a step of coating release film substrates with the adhesive coating solution to form adhesive coating films; Step (d) a step of irradiating the adhesive coating films with ultraviolet rays to produce an acrylic-based polymer B having a weight average molecular weight of 350,000 to 650,000 by photopolymerization of the unreacted portion of the acrylic-based monomer in the adhesive coating films in the absence of a cross-linking agent, whereby the acrylic-based adhesive layers are formed from a cured resin composition containing the acrylic-based polymer A, the acrylic-based polymer B, and the adhesion-imparting polymer, wherein a molecular weight distribution of the cured resin composition measured by gel permeation chromatography using tetrahydrofuran as an eluent is 2.4 to 4.4; and Step (e) a step of laminating the acrylic-based adhesive layers on the release film substrates to respective sides of an electron beam cross-linked polyethylene foam substrate; wherein the weight average molecular weights are determined by gel permeation chromatography using tetrahydrofuran as an eluent. Step (a) a step of irradiating a solvent-free photopolymerizable monomer composition containing an acrylic-based monomer and a photopolymerization initiator with ultraviolet rays to produce an acrylic-based polymer A having a weight average molecular weight of 700,000 to 3,000,000, preferably 750,000 to 1,000,000, by photopolymerization of the acrylic-based monomer in the absence of a cross-linking agent, whereby a polymer syrup containing the acrylic-based polymer A and an unreacted portion of the acrylic-based monomer is prepared, wherein ultraviolet irradiation conditions in the step (a) are such that ultraviolet irradiation is performed with rays at a wavelength of 250 to 400 nm applied at a power of 15 to 100 mW/cm 2 for 10 to 60 seconds in an inert gas atmosphere at a polymerization start temperature of 25 to 130°C, and is repeated 5 to 20 times at idling intervals of 20 to 40 seconds; Step (b) a step of mixing an adhesion-imparting polymer having a weight average molecular weight of 2,000 to 10,000 with the polymer syrup to prepare an adhesive coating solution; Step (c) a step of coating release film substrates with the adhesive coating solution to form adhesive coating films; Step (d) a step of irradiating the adhesive coating films with ultraviolet rays to produce an acrylic-based polymer B having a weight average molecular weight of 350,000 to 650,000 by photopolymerization of the unreacted portion of the acrylic-based monomer in the adhesive coating films in the absence of a cross-linking agent, whereby the acrylic-based adhesive layers are formed from a cured resin composition containing the acrylic-based polymer A, the acrylic-based polymer B, and the adhesion-imparting polymer, wherein a molecular weight distribution of the cured resin composition measured by gel permeation chromatography using tetrahydrofuran as an eluent is 2.4 to 4.4; and Step (e) a step of laminating the acrylic-based adhesive layers on the release film substrates to respective sides of an electron beam cross-linked polyethylene foam substrate;