To dispense with a spring for applying pressure contacting force so as to reduce the number of parts and the assembling cost by integratedly forming arms on a second receiving base supporting a first receiving base stuck with a friction pad.

A first receiving base 31 with a friction pad 25 is provided with fulcrum parts 31a, 31a on the right and left positions, and these are rotatably supported with the fulcrum receiving parts 33a, 33a on the right and left positions of a second receiving base 33. The second receiving base 33 is fixed to a stay 36 on the main body side of the device, and provided with a plurality of arms 39 made of resin molding for example. This arm 39 is formed into a cantilever type so as to be inclined at a fixed angle θ against the second receiving base 33 integratedly molded with itself. The extreme end part 39a of the arm 39 is curved, and when the first receiving base 31 is assembled with the second receiving base 33, the underside of the first receiving base 31 is supported by elasticity of the arms 39. By constituting the second receiving base in this way, it is unnecessary to use a spring, and the number of parts and the assembling cost can be reduced.