A sealing agent for a photoelectric conversion device which comprises one or more of a compound having a glycidyl structure, a compound having a cyclohexene oxide structure, a compound having an oxetane structure and a compound having a vinyl ether structure, and a cationic polymerization initiator; a photoelectric conversion device using the sealing agent; and a solar cell comprising the photoelectric conversion device. The sealing agent for a photoelectric conversion device can be used for pasting together upper and lower electroconductive glass substrates at an ordinary temperature in the manufacture of a photoelectric conversion device, and is excellent with respect to adhesion strength and the reliability in moisture resistance.