Abstract: Recognition of a position of a printed board is performed both before and after a chip component is mounted on the printed board. When a difference between the positions recognized before and after that is out of a predetermined allowable range, the printed board is treated as a defective. A CPU compares positions of a positioning mark provided on a printed board recognized both before and after a chip component is mounted on the printed board, the positions being taken an image by a board recognition camera and recognized by a recognition processing device. The CPU checks whether or not a difference between the positions is within a predetermined range stored in a RAM, that is, within a range from ?0.100 mm to +0.0100 mm, in both X and Y directions. When judging that the difference is within the range, the CPU controls an electronic component mounting apparatus to stop because of an error.