The invention of the present application addresses the problem of providing a binder for electrochemical cells which exhibits sufficient adhesive properties with respect to collectors and active materials, which is electrochemically stable, which is not readily swelled by electrolytes, and with which battery cycle characteristic can be sufficiently improved. Accordingly, provided is a binder for electrochemical cells which comprises a polyolefin copolymer (A) including structural units derived from an olefin, and structural units derived from (meth)acrylic acid. The carboxylic acid included in the structural units derived from the (meth)acrylic acid is neutralized by at least one non-volatile alkali compound and at least one volatile alkali compound.