PURPOSE: To obtain a polyorganosiloxane elastomer uncured at ordinary temperature, capable of curing in a short time by heating, providing a cured product having excellent adhesiveness and oil resistance and useful for gasket and packing material, etc., by heat-curing a specific curable polyorganosiloxane composition at a specific temperature.

CONSTITUTION: A curable polyorganosiloxane composition containing (A) 100 pts.wt. α,ω-dihydroxypolydiorganosiloxane of formula I [R1 and R2 are each a (substituted) monovalent hydrocarbon group; (m) is a number capable of providing 100-200000cSt viscosity at 25°C], (B) 0.5-20 pts.wt. compound of the formula R3aSi(ON=X)4-a [R3 is R1; X is a group of CR42 (R4 is R1) or a group of formula II (R5 is a (substituted) divalent hydrocarbon group; (a) is 0 or 1)] or its partial hydrolysis condensation product and (C) 0.1-10 pts.wt. compound of the formula R6Si(OR7)3 [R6 is R1; R7 is a 1-8C (substituted) monovalent hydrocarbon group] or its partial hydrolysis condensation product and not containing a curing catalyst having metal in the molecule is cured by heating at 50-200°C to provide the objective elastomer.