A
radiation-curable composition capable of giving a cured product which has excellent transparency,
mechanical strength and an excellent balance between surface
hardness and resistance to deformation by heat /
humidity; the cured product; and a multilayer structure which has a layer of the cured product and is suitable for use as an
optical recording medium, etc, are provided A
radiation-curable composition which comprises a
monomer having a
radiation-curable group and gives a cured product having the following properties: (1) when the cured product has a thickness of 100±5 μm, the cured product has a light
transmittance at a
wavelength of 550 nm of 80% or higher; (2) a multilayer structure where a layer of the cured product having a thickness of 100±5 μm is formed on a poly(
ethylene terephthalate) film having a thickness of 100±5 μm, has a surface
hardness of HB or higher; and (3) when a multilayer structure where the cured product having a thickness of 100±5 μm is formed on a disk made of a
polycarbonate having a
diameter of 130 mm and a thickness of 1.2±0.2 mm, is placed in an environment of 80° C. and 85% RH for 100 hours, then an absolute value |a| of an amount of warpage, a (mm), on the circumference of the multilayer structure is 0.5 mm or less.