A composition for an encapsulant, comprising: 1) a first copolymer comprising a first unit represented by the following chemical Formula 1, a second unit represented by the following Chemical Formula 2, and a third unit represented by the following Chemical Formula 3; 2) a second copolymer comprising the second unit represented by the following Chemical Formula 2 and the third unit represented by the following Chemical Formula 3; 3) one or more photoinitiators; and a reactive silicone-based oligomer represented by the following Chemical Formula 5, wherein based on the total weight of the composition for an encapsulant, the content of the first copolymer is 20 to 60 wt%, the content of the second copolymer is 10 to 30 wt%, the content of the photoinitiator is 0.1 to 10 wt%, and the content of the reactive silicone-based oligomer is 20 to 60 wt%: in Chemical Formulae 1 to 3, R1 is a direct bond, or an alkylene group, R2 and R7 are a vinyl group, an acrylate group, or a methacrylate group, R3 to R6 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, an alkyl group, an alkenyl group, an aryl group, a glycidyl group, an isocyanate group, a hydroxy group, a carboxyl group, a vinyl group, an acrylate group, a methacrylate group, an epoxide group, a cyclic ether group, a sulfide group, an acetal group, a lactone group, an amide group, an alkylaryl group, an alkylglycidyl group, an alkylisocyanate group, an alkylhydroxy group, an alkylcarboxyl group, an alkylvinyl group, an alkylacrylate group, an alkylmethacrylate group, an alkyl cyclic ether group, an alkylsulfide group, an alkylacetal group, an alkyl lactone group, and an alkyl amide group, and a, b, c, and d are each independently 1 to 200. 1) a first copolymer comprising a first unit represented by the following chemical Formula 1, a second unit represented by the following Chemical Formula 2, and a third unit represented by the following Chemical Formula 3; 2) a second copolymer comprising the second unit represented by the following Chemical Formula 2 and the third unit represented by the following Chemical Formula 3; 3) one or more photoinitiators; and a reactive silicone-based oligomer represented by the following Chemical Formula 5, wherein based on the total weight of the composition for an encapsulant, the content of the first copolymer is 20 to 60 wt%, the content of the second copolymer is 10 to 30 wt%, the content of the photoinitiator is 0.1 to 10 wt%, and the content of the reactive silicone-based oligomer is 20 to 60 wt%: in Chemical Formulae 1 to 3, R1 is a direct bond, or an alkylene group, R2 and R7 are a vinyl group, an acrylate group, or a methacrylate group, R3 to R6 are the same as or different from each other, and are each independently selected from the group consisting of hydrogen, an alkyl group, an alkenyl group, an aryl group, a glycidyl group, an isocyanate group, a hydroxy group, a carboxyl group, a vinyl group, an acrylate group, a methacrylate group, an epoxide group, a cyclic ether group, a sulfide group, an acetal group, a lactone group, an amide group, an alkylaryl group, an alkylglycidyl group, an alkylisocyanate group, an alkylhydroxy group, an alkylcarboxyl group, an alkylvinyl group, an alkylacrylate group, an alkylmethacrylate group, an alkyl cyclic ether group, an alkylsulfide group, an alkylacetal group, an alkyl lactone group, and an alkyl amide group, and a, b, c, and d are each independently 1 to 200.