A method of fixing a toner image on a supporting member by bringing the supporting member supporting thereon the toner image into pressure contact with a fixing roller, wherein an elasticity improving agent for increasing the elasticity of the toner upon coming into contact with the toner is disposed on a member which comes into direct or indirect contact with the outer circumferential surface of the fixing roller.The elasticity improving agent is a material causing the reaction which increases the molecular weight of the binder resin of the binder and/or a reaction promoter for such a reaction.The elasticity improving agent is selected from a group consisting of:(a) agents which are capable of enhancing the elasticity of toner material,(b) polyhydric alcohols,(c) polyvalent amines and(d) polyvalent carboxylic acids.