TWI846961B

The present invention provides: a curable composition containing the component (A) and component (C) described below; a cured product obtained by curing the curable composition; and a method for using the curable composition as an adhesive for optical element fixing material or as a sealing material for optical element fixing material. This curable composition has a high refractive index and is suitably used in the optics industry. Component (A): a polysilsesquioxane compound which has repeating units [repeating units (1)] represented by formula (a-1) [wherein R1 represents an unsubstituted aryl group having 6-12 carbon atoms or a substituted aryl group having 6-12 carbon atoms] and repeating units [repeating units (2)] represented by formula (a-2) [wherein R2 represents an unsubstituted alkyl group having 1-10 carbon atoms or a substituted alkyl group having 1-10 carbon atoms] and which is characterized by satisfying a specific requirement relating to the molecular structure. Component (C): a silane coupling