NOVELTY - An easily adhesive agent contains (meth)acrylic-type copolymer (A) having glass transition temperature of 10-100 degrees C and number average molecular weight of 15000-250000, epoxy resin (Ep) and polyisocyanate compound (B) containing 0.1-5 isocyanate groups with respect to 1 hydroxyl group of component (A). The content of epoxy resin is 1-100 pts. wt. with respect to 100 pts. wt. (meth)acrylic-type copolymer (A). The easily adhesive agent contains carbon-carbon double bond derived from (meth)acryloyl group, and has iodine number of 0.01-50 g/100 g.    USE - Easily adhesive agent is used for protection sheet for solar cell module (all claimed).    ADVANTAGE - The easily adhesive agent has excellent adhesiveness and bond durability. Even if the solar cell protection sheet is exposed to high temperature and high humidity for long period of time, the suppression of output of solar cell module is suppressed.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) protection sheet, which has easily adhesive layer (1') as an outermost surface and plastic film (2) which supported easily adhesive layer (1'). The easily adhesive layer (1') is formed of easily adhesive agent; and    (2) solar cell module, which has a solar cell surface protective material (I) located in the light-receiving surface of the solar cell, sealing material (II) located in the light receiving surface of solar cell, photovoltaic cell (III), sealing material (IV) located in the non-light receiving surface side of solar cell, and solar cell back surface protective material (V) located in the non-light receiving surface of solar cell. At least one of solar cell surface protective material or solar cell back surface protective material arrange on protection sheet for solar cells, so that easily adhesive layer optionally contacts the sealing material at the side of light-receiving surface, or sealing material at the surface of non-light-receiving surface. The easily adhesive layer is then hardened to obtain solar cell module.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of solar cell module.    Solar cell surface protective material located in the light-receiving surface of photovoltaic cell (I)    Sealing material located in the light-receiving surface of photovoltaic cell (II)    Photovoltaic cell (III)    Sealing material located in the non-light-receiving surface of photovoltaic cell (IV)    Solar cell back surface protective material located in the non-light-receiving surface of photovoltaic cell (V)