To provide a composition for a solar cell module sealing material for obtaining a sealing material sheet having a member adjacent the sealing material sheet and an excellent (air tightness) adhesion.

A composition for a soller cell module sealing material comprises polyolefin resin having a water vapor permeability according to JIS-K7129 in the thickness of 200 μm or more is equal to or less than 10 g/(m² day atm), and/or copolymer made by copolymerizing ionomer resin, tackifier, α-olefin and ethylene-modified unsaturated silane compound while using them as co-monomers, or silane coupling agent including mercapto group. The tackifier has a softening temperature of 85°C or more and an acid number according to JIS-K2501 of 0 mgKOH/g or more and less than 5 mgKOH/g.