In the field of electronic component mounting, electronic component mounting apparatuses including a moving device for moving the mounting head horizontally with respect to a working plane have been widely used. As this horizontal moving device, a Cartesian robot (X-Y robot) composed of a first linear-motion device for moving the mounting head in a first direction (X direction) extending along the working plane and a second linear-motion device for moving the first linear-motion device in a second direction (Y direction) orthogonal to the first direction is widely used. In such an electronic component mounting apparatus, the mounting head is movable within a rectangular plane of which two sides orthogonal to each other are given by respective moving axes of the first linear-motion device and the second linear-motion device. See, e.g., Japanese patent publication No. 2740682.