A vehicular communication system includes: a vehicular communication apparatus; and a portable terminal apparatus. The vehicular communication apparatus includes: a vehicular storage device that stores a predetermined vehicular application for a predetermined function; and a vehicular input device that enters an operation for the predetermined function. The portable terminal apparatus includes: a mobile storage device that stores a predetermined mobile application for the predetermined function; a mobile input device that enters an operation for the predetermined function; an interoperation detection device that detects establishment of an interoperation state, in which the predetermined vehicular application and the predetermined mobile application interoperate with each other; and an operation input disable device that prevents the mobile input device from entering the operation when the interoperation detection device detects the establishment of the interoperation state.