A small electronic apparatus such as an electronic organizer, electronic memo, etc. is disclosed which has a memory for storing data, and a communication unit for transmitting data stored in the memory to another electronic apparatus, and for receiving data from the other electronic apparatus. The apparatus selects, before transmitting at least one portion of said data, either of an add mode (transmitted data is added to data stored in the other electronic apparatus) and a update mode (data stored in the other electronic apparatus is replaced with the transmitted data). The apparatus has a signal unit for, when the add mode is selected, transmitting a first signal indicative that the add mode is selected to the other electronic apparatus, and for, when the update mode is selected, transmitting a second signal indicative that the update mode is selected to the other electronic apparatus. The apparatus displays data which has been transmitted when a data transmission error has occurred.