a novel anaerobically curable resin composition of one - part type is provided . the composition consists essentially of the following components , and in the specified amounts ; the component being a mixture of polymerizable components consisting of an addition - reaction product of a polybutadiene - based liquid rubber , a polyisocyanate and a hydroxyl group - containing methacrylate , and a polymerizable methacrylate ; the component being a salt of o - benzoic sulfimide with a specified amine ; and the component being an ammonium or amine salt of an aminopolycarboxylic acid . the process for preparation of the composition comprises the step of adding the specified amounts of the aminopolycarboxylic acid or an alkali metal salt thereof and an ammonia water or a volatile organic amine to the component , the step of stirring and heating the mixture to remove volatile matters partly until the ph is decreased to 9 or lower , and the step of adding thereto the component .