To prevent the generation of a component of a pressing force by forming the inclined surface of a pressure foot into a truncated cone-like surface, the dimensions of which is the same as the recessed part of a rotary member.

When a pressure foot 6 is lowered to bring a rotary member 20 into contact with a printed board 4, the reactive force of a pressing force of the rotary member is received by a contact surface of the truncated cone-like slope of the rotary member 20 with the truncated cone-like slope of the pressure foot 6. At this time, when at least a part of the contact surface is arranged to be at right angles to the direction in which the pressing force acts, no component in the direction perpendicular to the axis of a supporting shaft 9 is generated in the rotary member 20. Therefore, no excess load is applied to a bearing 11 or the supporting shaft 9, and thus the supporting shaft 9 or the bearing 11 is not damaged.