NOVELTY - A resin composition contains an epoxy compound (A), photocationic polymerization initiator, and reaction accelerator. The epoxy compound (A) is 7-oxabicyclo heptane-type compound (1A) and/or oxirane-type compound (1B). The reaction accelerator is alicyclic epoxy compound (II). The ratio of epoxy compound (A) with respect to alicyclic epoxy compound (II) is 60:40-99:1.    USE - Resin composition is used for resin cured material and transparent composite for substrate for display elements and substrate for surface light sources (all claimed). Uses include but are not limited to substrate for liquid crystal display element, substrate for organic electroluminescent element, substrate for color filter, substrate for electronic paper, substrate for solar cell, and touch panel substrate.    ADVANTAGE - The resin cured material having reduced water absorption property, is formed using the resin composition with reduced consumption of energy.    DETAILED DESCRIPTION - A resin composition contains an epoxy compound (A), photocationic polymerization initiator, and reaction accelerator. The epoxy compound (A) is 7-oxabicyclo heptane-type compound of formula (1A) and/or oxirane-type compound of formula (1B). The reaction accelerator is alicyclic epoxy compound of formula (II). The ratio of epoxy compound (A) with respect to alicyclic epoxy compound (II) is 60:40-99:1.    R1=organic groups excluding structure (II);    R2=organic groups;and    X=-O-, -S-, -SO-, -SO2-, -CH2-, -CH(CH3)-, -C(CH2)3- or single bond.    INDEPENDENT CLAIMS are included for the following:    (1) resin cured material (1), which is produced by light-irradiating the resin composition; and    (2) transparent composite, which is obtained by compounding glass filler with resin composition, and light-irradiating.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of substrate for surface light source.    Resin cured material (1)    Vertical direction glass yarn (2a)    Horizontal direction glass yarn (2b)    Substrate for surface light source (100)