A colorimeter comprising: (a) a colorimetry unit that performs colorimetry processing with respect to a target; (b) a first storage unit that stores data relevant to a colorimetry result of the colorimetry unit; (c) a second storage unit that stores data relevant to a colorimetry result of the colorimetry unit; (d) a control unit that stores the same colorimetry data indicating a color of the target which is obtained by the colorimetry processing of the colorimetry unit, in each of the first storage unit and the second storage unit, when the colorimetry processing is performed by the colorimetry unit; and (e) a communication unit that performs data communication with respect to an external device, wherein the control unit performs mirroring processing in which first data is stored in the second storage unit according to the presence of the first data which is stored in the first storage unit and is not stored in the second storage unit, and second data is stored in the first storage unit according to the presence of the second data which is not stored in the first storage unit and is stored in the second storage unit, the communication unit realizes each of data communication of a first method according to mass storage control and data communication of a second method according to serial communication control, with respect to the external device, with respect to a request of deleting the data stored in the first storage unit from the external device according to the data communication of the first method, a state in which data is not deleted from the first storage unit and the data stored in the first storage unit is maintained, and with respect to a request of deleting the data stored in the first storage unit from the external device according to the data communication of the second method, data is deleted from the first storage unit and a response indicating the effect is transmitted to the external device, wherein the first data is data stored in the first storage unit and the second data is data stored in the second storage unit, the first and second data comprising data relevant to a colorimetry result. (a) a colorimetry unit that performs colorimetry processing with respect to a target; (b) a first storage unit that stores data relevant to a colorimetry result of the colorimetry unit; (c) a second storage unit that stores data relevant to a colorimetry result of the colorimetry unit; (d) a control unit that stores the same colorimetry data indicating a color of the target which is obtained by the colorimetry processing of the colorimetry unit, in each of the first storage unit and the second storage unit, when the colorimetry processing is performed by the colorimetry unit; and (e) a communication unit that performs data communication with respect to an external device, wherein the control unit performs mirroring processing in which first data is stored in the second storage unit according to the presence of the first data which is stored in the first storage unit and is not stored in the second storage unit, and second data is stored in the first storage unit according to the presence of the second data which is not stored in the first storage unit and is stored in the second storage unit, the communication unit realizes each of data communication of a first method according to mass storage control and data communication of a second method according to serial communication control, with respect to the external device, with respect to a request of deleting the data stored in the first storage unit from the external device according to the data communication of the first method, a state in which data is not deleted from the first storage unit and the data stored in the first storage unit is maintained, and with respect to a request of deleting the data stored in the first storage unit from the external device according to the data communication of the second method, data is deleted from the first storage unit and a response indicating the effect is transmitted to the external device, wherein the first data is data stored in the first storage unit and the second data is data stored in the second storage unit, the first and second data comprising data relevant to a colorimetry result.