Curable composition

A modified polyorganosiloxane compound having two or more epoxy group and/or oxetanyl group in a molecule, the compound being a hydrosilylation reaction product of the following compounds:

• (α1) an organic compound having 2 to 6 carbon-carbon double bonds reactive with a SiH group in a molecule;
• (β1) a linear and/or cyclic polyorganosiloxane compound having at least two SiH groups in a molecule;
• and
• (β1) a cyclic polyorganosiloxane compound having at least two Sill groups in a molecule;
• and
• (γ1) an organic compound having at least one epoxy group or oxetanyl group and one carbon-carbon double bond reactive with a SiH group in a molecule;
• wherein the compound (β1) is a cyclic polyorganosiloxane compound having a SiH group represented by the following general formula (II):
• wherein, R2 represents an organic group having 1 to 6 carbon atoms;
• and n represents an integer of 3 to 10,
• wherein the compound (γ1) is at least one selected from the group consisting of 1,2-epoxy-4-vinylcyclohexane and 3-ethyl-3-allyloxymethyloxetane,
• wherein the ratio Y/X of the total number (X) of the carbon-carbon double bonds reactive with the SiH group in the compound (α1) and the total number (Y) of the SiH groups in the compound (β1) is no less than 3, and
• wherein the ratio X′/Y′ of the total number (X′) of the carbon-carbon double bonds reactive with the SiH group in the compound (γ1), and the total number (Y′) of the SiH groups in the reaction product of the compound (α1) and the compound (β1) after removing the unreacted compound (β1) is no greater than ⅔.