A silicone rubber-based hardening composition includes a linear organopolysiloxane having a vinyl group (A), an organohydrogen polysiloxane (B), and a silica filler (C) of which surface is treated with a silane coupling agent having a trimethylsilyl group. The linear organopolysiloxane having a vinyl group (A) includes a first linear organopolysiloxane having a vinyl group (A1), and a second linear organopolysiloxane having a vinyl group (A2).
