An information processing system comprising: an input device (3, 4); and a main body apparatus which can communicate with the input device, the input device including a first operation portion, a second operation portion and a transmission unit (101, 111) which transmits operation data (500, 510, 520) representing an operation by a user to the main body apparatus, wherein each of the first operation portion and the second operation portion comprises one or more operation buttons, the main body apparatus including a storage unit in which an operation scheme of the input device is registered, a reception unit which receives the operation data transmitted from the transmission unit, a registration unit which registers the operation scheme of the input device in the storage unit as a first operation scheme in vertical holding of the input device when the operation data (510, 520) received by the reception unit indicates a first operation of the first operation portion and registers the operation scheme of the input device in the storage unit as a second operation scheme in lateral holding of the input device when the operation data received by the reception unit indicates a second operation of the second operation portion, and a processing unit which performs processing based on the operation scheme registered in the storage unit onto the operation data received by the reception unit. an input device (3, 4); and a main body apparatus which can communicate with the input device, the input device including a first operation portion, a second operation portion and a transmission unit (101, 111) which transmits operation data (500, 510, 520) representing an operation by a user to the main body apparatus, wherein each of the first operation portion and the second operation portion comprises one or more operation buttons, the main body apparatus including a storage unit in which an operation scheme of the input device is registered, a reception unit which receives the operation data transmitted from the transmission unit, a registration unit which registers the operation scheme of the input device in the storage unit as a first operation scheme in vertical holding of the input device when the operation data (510, 520) received by the reception unit indicates a first operation of the first operation portion and registers the operation scheme of the input device in the storage unit as a second operation scheme in lateral holding of the input device when the operation data received by the reception unit indicates a second operation of the second operation portion, and a processing unit which performs processing based on the operation scheme registered in the storage unit onto the operation data received by the reception unit. a storage unit in which an operation scheme of the input device is registered, a reception unit which receives the operation data transmitted from the transmission unit, a registration unit which registers the operation scheme of the input device in the storage unit as a first operation scheme in vertical holding of the input device when the operation data (510, 520) received by the reception unit indicates a first operation of the first operation portion and registers the operation scheme of the input device in the storage unit as a second operation scheme in lateral holding of the input device when the operation data received by the reception unit indicates a second operation of the second operation portion, and a processing unit which performs processing based on the operation scheme registered in the storage unit onto the operation data received by the reception unit.