The present invention relate to a novel silane coupling agent and a medical and/or dental curable composition comprising the same. It is an object of the present invention to provide a novel silane coupling agent that imparts high affinity to a radical polymerizable monomer, thereby imparting high mechanical strength, flexibility and durability when used for a medical and/or dental curable composition, and an inorganic filler surface-treated with the novel silane coupling agent and a novel medical and/or dental curable composition. A silane coupling agent including repeating units such as a urethane bond and polyethylene glycol (ether bond) at a specific position is used.