NOVELTY - The coating apparatus (10) has spline shaft (30) arranged in interior of workpiece storage chamber (12), in parallel to ball screw shaft (18) for Y-axes. A nut (32) moves along axial direction of spline shaft, with rotation of shaft (18). A rotation direction conversion mechanism converts rotation direction to 90 degrees , and transmits rotational force of nut to ball screw shaft (58) for X-axes arranged orthogonal to spline shaft. A coating gun (62) moves along axial direction of ball screw shaft (58), with rotation of ball screw shaft (58), for coating a sheet (16) in chamber.    USE - Coating apparatus used for coating electrolytic membrane sheet used for electrode of fuel cell for motor vehicle.    ADVANTAGE - The structure of the mechanism that transmits driving force of each motor to coating gun, and the structure of the rotation direction conversion mechanism can be simplified. Hence the structure of the coating apparatus can be simplified.    DETAILED DESCRIPTION - The rotation direction conversion mechanism comprises pulleys (44,46), timing belt (48), rotating shaft (50), and bevel gear pairs (52,54). The apparatus has couplings (22,36) connected to thread portions of the shafts (18,30) respectively, and servomotors (26,40) arranged in exterior of the chamber, to rotationally drive the ball screw shaft (18) and spline shaft respectively. A housing (20) moves along axial direction of ball screw shaft (18), with rotation of the ball screw shaft (18). A bearing (34) is fixed to the housing, to rotatably supports the nut.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross sectional top view of principal portion of the coating apparatus.    Coating apparatus (10)    Workpiece storage chamber (12)    Sheet (16)    Ball screw shaft for Y-axes (18)    Housing (20)    Couplings (22,36)    Servomotors (26,40)    Spline shaft (30)    Nut (32)    Bearing (34)    Pulleys (44,46)    Timing belt (48)    Rotating shaft (50)    Bevel gear pairs (52,54)    Ball screw shaft for X-axes (58)    Coating gun (62)