A component mounting apparatus having a work conveyor-positioner unit is arranged on a supporting base to convey and position a substrate in an X direction. Supporting frames extend vertically from ends of the supporting base and face each other in a Y direction. The component mounting apparatus further includes a plurality of Y-axis tables extending between upper ends of the supporting frames, X-axis tables attached to movable portions of the Y-axis tables, and operating heads attached to movable portions of the X-axis tables to perform operations with respect to the substrate on the work conveyor-positioner unit. Each of the plurality of the Y-axis tables includes a movable portion at a lower part. Each of the X-axis tables includes a movable portion at a lower part and the operating heads are attached to a lower part of the movable portion of the X-axis tables.