To provide a cross-linking agent for a silicone rubber without having a problem in safety and hygiene because of not generating a compound having a high toxicity as a decomposition product, and especially excellent in a point of without forming voids in a cross-linked material obtained by performing a hot gas cross-linking, a silicone rubber composition, a method for cross-linking the silicone rubber, a silicone rubber-covered electric cable and a silicone rubber tube.

This cross-linking agent for the silicone rubber consists of solid particles having ≥0.1 and <5 μm mean primary particle diameter of an organic peroxide not containing chlorine atom. The silicone rubber composition contains (A) an organopolysiloxane, (B) a reinforcing filler and (C) the cross-linking agent for the silicone rubber as essential components by 100 pts.wt. component (A), 1-400 pt.wt. component (B), and component (C) in an amount so as to become 0.1-10 mmol as peroxide bonds based on 100 g of the total amount of the components (A) and (B).