A printer, comprising: an input device (14, 40) configured to receive input of a product code for identifying a product; a communication interface configured to request product information corresponding to the input product code and receive the product information from an external device, the product information including information on the product; a memory device configured to record, for each product code, product information corresponding to the product code and an update date of the product information, wherein the memory device is further configured to update the product information corresponding to the input product code when the product information is received from the external device via the communication interface, the recorded product information for some or all product codes being also updated every time the communication interface receives product information transmitted from the external device at predetermined timing, the update date recorded in the memory device being information indicating the date on which the product information of the memory device is updated with the product information of the external device; the printer further comprising: a print device configured to print the product information on a recording medium, the product information corresponding to the product code input from the input device; a display device configured to display one of the product information received via the communication interface and the product information recorded in the memory device, as product-information-to-be-printed to be printed by the print device; and a controller device configured to read, when the communication interface is incapable of receiving the product information from the external device, the product information corresponding to the product code input from the input device, from the memory device, control the display device to display the read product information as the product-information-to-be-printed, in a display mode indicating that the product-information-to-be-printed is product information recorded in the memory device, in which display mode the update date of the product information is indicated and control the print device to print the product information displayed on the display device; wherein the controller is further configured to control the display device to display the product-information-to-be-printed with an operation button for accepting an operation to change the product-information-to-be-printed; wherein, upon user selection of the operation button and subsequent acceptance of user operation to change the product-information-to-be-printed, the controller is configured to control the display device to display the changed product-information-to-be-printed. an input device (14, 40) configured to receive input of a product code for identifying a product; a communication interface configured to request product information corresponding to the input product code and receive the product information from an external device, the product information including information on the product; a memory device configured to record, for each product code, product information corresponding to the product code and an update date of the product information, wherein the memory device is further configured to update the product information corresponding to the input product code when the product information is received from the external device via the communication interface, the recorded product information for some or all product codes being also updated every time the communication interface receives product information transmitted from the external device at predetermined timing, the update date recorded in the memory device being information indicating the date on which the product information of the memory device is updated with the product information of the external device; a print device configured to print the product information on a recording medium, the product information corresponding to the product code input from the input device; a display device configured to display one of the product information received via the communication interface and the product information recorded in the memory device, as product-information-to-be-printed to be printed by the print device; and a controller device configured to read, when the communication interface is incapable of receiving the product information from the external device, the product information corresponding to the product code input from the input device, from the memory device, control the display device to display the read product information as the product-information-to-be-printed, in a display mode indicating that the product-information-to-be-printed is product information recorded in the memory device, in which display mode the update date of the product information is indicated and control the print device to print the product information displayed on the display device; wherein the controller is further configured to control the display device to display the product-information-to-be-printed with an operation button for accepting an operation to change the product-information-to-be-printed; wherein, upon user selection of the operation button and subsequent acceptance of user operation to change the product-information-to-be-printed, the controller is configured to control the display device to display the changed product-information-to-be-printed.