The present invention aims to provide a method for modifying a surface of a rubber vulcanizate and a gasket for syringes, which can provide a variety of functions, including sliding properties, liquid leakage resistance, and protein adsorption resistance. Provided is a surface modification method for modifying a surface of a rubber vulcanizate having a Shore A hardness of 55 to 90 as a modification target, the method including: step 1 of adding a silane compound to the surface of the modification target； and step 2 of reacting at least a fluoroalkyl group-containing silane compound to form a surface-modified layer.
