A release paper or film-forming silicone composition of addition cure type comprising 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups per molecule and having an alkenyl content of 0.001 to 0.2 mol/100 g and a 30 wt% toluene dilution viscosity at 25°C of 0.01 to 70 Pa·s, an adhesion improving component in the form of the following compounds and: 0.1 to 30 parts by weight of a compound containing at least two alkenyl groups per molecule, having an alkenyl content corresponding to 5 to 1,000 times the alkenyl content of component, being free of epoxy groups, and having a viscosity at 25°C of less than 1 Pa·s or a 30 wt% toluene dilution viscosity of less than 0.1 Pa·s, and 0.1 to 20 parts by weight of an organopolysiloxane containing at least 30 mol% per molecule of siloxane units having an epoxycyclohexyl group bonded to a silicon atom via a carbon atom, being free of alkenyl groups, and having an average degree of polymerization of 2 to 50, an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in such an amount that the moles of silicon-bonded hydrogen atoms corresponds to 0.5 to 10 times the moles of alkenyl groups in components and, a catalytic amount of a platinum group metal base catalyst, and 0 to 20,000 parts by weight of an organic solvent or water. 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups per molecule and having an alkenyl content of 0.001 to 0.2 mol/100 g and a 30 wt% toluene dilution viscosity at 25°C of 0.01 to 70 Pa·s, an adhesion improving component in the form of the following compounds and: 0.1 to 30 parts by weight of a compound containing at least two alkenyl groups per molecule, having an alkenyl content corresponding to 5 to 1,000 times the alkenyl content of component, being free of epoxy groups, and having a viscosity at 25°C of less than 1 Pa·s or a 30 wt% toluene dilution viscosity of less than 0.1 Pa·s, and 0.1 to 20 parts by weight of an organopolysiloxane containing at least 30 mol% per molecule of siloxane units having an epoxycyclohexyl group bonded to a silicon atom via a carbon atom, being free of alkenyl groups, and having an average degree of polymerization of 2 to 50, 0.1 to 30 parts by weight of a compound containing at least two alkenyl groups per molecule, having an alkenyl content corresponding to 5 to 1,000 times the alkenyl content of component, being free of epoxy groups, and having a viscosity at 25°C of less than 1 Pa·s or a 30 wt% toluene dilution viscosity of less than 0.1 Pa·s, and 0.1 to 20 parts by weight of an organopolysiloxane containing at least 30 mol% per molecule of siloxane units having an epoxycyclohexyl group bonded to a silicon atom via a carbon atom, being free of alkenyl groups, and having an average degree of polymerization of 2 to 50, an organohydrogenpolysiloxane containing at least two silicon-bonded hydrogen atoms per molecule, in such an amount that the moles of silicon-bonded hydrogen atoms corresponds to 0.5 to 10 times the moles of alkenyl groups in components and, a catalytic amount of a platinum group metal base catalyst, and 0 to 20,000 parts by weight of an organic solvent or water.