A board work line comprising: a reflow furnace, an appearance inspector located at an end of the board work line, wherein the appearance inspector is disposed downstream from the reflow furnace; an image data storage device for storing images acquired by a board work machine of the board work line, the image data storage device comprising: an instruction section configured to instruct storage of image data acquired by the board work machine that executes a predetermined board work on a board, with respect to the board work after an inspection result is obtained, based on the inspection result, wherein the board is a circuit board, wherein the instruction section is configured to receive the inspection result from the appearance inspector, wherein the appearance inspector is configured for obtaining the inspection result by inspecting whether the board work is good or no-good in the board work machine, wherein the instruction section causes the image data to be stored by reducing the number of gradation bits of the image data when the inspection result by the appearance inspector is good as compared with when the inspection result by the appearance inspector is no-good wherein the board work machine is a component mounter configured to mount a component on the board, and wherein the appearance inspector is configured to recognize appropriateness and mounting states of each of multiple components mounted on the board. a reflow furnace, an appearance inspector located at an end of the board work line, wherein the appearance inspector is disposed downstream from the reflow furnace; an image data storage device for storing images acquired by a board work machine of the board work line, the image data storage device comprising: an instruction section configured to instruct storage of image data acquired by the board work machine that executes a predetermined board work on a board, with respect to the board work after an inspection result is obtained, based on the inspection result, wherein the board is a circuit board, wherein the instruction section is configured to receive the inspection result from the appearance inspector, wherein the appearance inspector is configured for obtaining the inspection result by inspecting whether the board work is good or no-good in the board work machine, wherein the instruction section causes the image data to be stored by reducing the number of gradation bits of the image data when the inspection result by the appearance inspector is good as compared with when the inspection result by the appearance inspector is no-good wherein the board work machine is a component mounter configured to mount a component on the board, and wherein the appearance inspector is configured to recognize appropriateness and mounting states of each of multiple components mounted on the board. an instruction section configured to instruct storage of image data acquired by the board work machine that executes a predetermined board work on a board, with respect to the board work after an inspection result is obtained, based on the inspection result, wherein the board is a circuit board, wherein the instruction section is configured to receive the inspection result from the appearance inspector, wherein the appearance inspector is configured for obtaining the inspection result by inspecting whether the board work is good or no-good in the board work machine, wherein the instruction section causes the image data to be stored by reducing the number of gradation bits of the image data when the inspection result by the appearance inspector is good as compared with when the inspection result by the appearance inspector is no-good wherein the board work machine is a component mounter configured to mount a component on the board, and wherein the appearance inspector is configured to recognize appropriateness and mounting states of each of multiple components mounted on the board.