An insulation paste for forming a protective layer of a solar cell device includes: a siloxane resin; an organic solvent; and multiple fillers each having a surface covered with an organic coating containing at least one material different from a material of the siloxane resin. A method for producing the insulation paste includes: preparing the multiple fillers; and mixing together a precursor of the siloxane resin, water, a catalyst, an organic solvent, and the multiple fillers. A method for manufacturing a solar cell device includes: applying the insulation paste to the passivation layer; and drying the insulation paste to form the protective layer on the passivation layer. A solar cell device includes: the passivation layer located on a semiconductor region; and the protective layer located on the passivation layer and including a siloxane resin and dimethylpolysiloxane.