A rotor shaft module for a rotor shaft of a molded-case circuit breaker, includes a module body including an electrically insulating first material, the module body including a receptacle for a contact element of the molded-case circuit breaker. The rotor shaft module includes at least one coupling apparatus for connection to an opposing coupling apparatus of a further rotor shaft module. In addition, disclosed are a rotor shaft for a molded-case circuit breaker includes at least two coupled rotor shaft modules; a molded-case circuit breaker including a rotor shaft; and a method for producing a rotor shaft module for a rotor shaft of a molded-case circuit breaker.