Provided is an olefin resin composition, and a method of manufacturing an encapsulant for an optoelectronic device, in which the encapsulant exhibits excellent adhesive strength with a back sheet and a front substrate included in various optoelectronic devices. In addition, the encapsulant does not have a bad influence on parts such as optoelectronic units or wiring electrodes encapsulated in an optoelectronic device, and a working environment, and can excellently maintain workability and economic feasibility of device manufacturing.