One embodiment of the present invention provides a new transparent double-sided adhesive sheet that, in bonding of image display device-constituting members provided with a step portion on the bonding surface thereof with a transparent double-sided adhesive sheet interposed therebetween, can conform to the step portion to fill every corner therewith, can also allow strain generated in the adhesive sheet to be relaxed, and furthermore can maintain foaming resistance under a high-temperature and/or high-humidity environment without impairment of handleability. One embodiment of the present invention proposes a transparent double-sided adhesive sheet in a B-stage state, in which, first, the transparent double-sided adhesive sheet contains at least one (meth)acrylate (co)polymer, an ultraviolet polymerization initiator (A) having a molar absorptivity at a wavelength of 365 nm of 10 or more and a molar absorptivity at a wavelength of 405 nm of 0.1 or less, and a visible light polymerization initiator (B) having a molar absorptivity at a wavelength of 405 nm of 10 or more, and, second, a value (E′/G′) obtained by dividing a dynamic storage elastic modulus (E′) at 60° C. determined by a tension method, by a dynamic storage elastic modulus (G′) at 60° C. determined by a shear method is 10 or more.