pressure adjusting means during the pivoting of the pedal arm a pivot supporting fastening pin 18 is coupled to the housing 10 and the pedal arm 12 provide pivot of the pedal arm 12 with respect to the housing 10 a pair of torsion springs 20 are fitted to the fastening pin 18 to elastically pivot the pedal arm 12 in relation to the housing 10 on one end of the pivot supporting fastening pin 18 there is a securing pin 22 for preventing the fastening pin 18 from becoming separated from the housing 10 and the pedal arm 12 as shown in fig3 the foot pressure adjusting means includes a friction plate 24 that is detachably coupled to the leading end of the pedal arm 12 the friction plate 24 includes an elastic installation part 24 a having a pair of inclinedly spread protuberance parts 24 b that couple to the leading end of the pedal arm 12 to maintain an elastic supporting force a contact part 24 c integrally extends from the elastic installation part 24 a to contact the contact member 16 also included is pair of securing support parts 24 d that integrally extend from both ends of the contact part 24 c the pair of securing support parts 24 d couple to the leading end of the pedal arm 12 and generate a securing strength the leading end of the pedal arm 12 has a mounting slot 12 a for elastically receiving the friction plate 24 the mounting slot 12 a receives the elastic installation part 24 a of the friction plate 24 the.