to screw with nut 34 for securing fore leg 3 and hind leg together in order to enable fore leg 3 to move pivotally in relation to hind leg 4 gasket 35 is placed between the both 3 and 4 inserted therethrough by shaft tube 32 the front section of fore leg 3 has two anti sliders 37 at both corners to prevent fore leg 3 from sliding on the ground hind leg 4 is u shaped having shaft hole 41 at the longitudinal center for shaft tube 32 to pass through for securing with fore leg 3 and pin hole 42 at both upper ends for pins 53 to insert for connecting with linking tubes 52 having pin holes 57 for pins 53 to insert the bending corners of hind leg 4 are covered with anti slide tubes 36 to prevent this chair from sliding on the ground and to keep the horizontal portion of hind leg 4 from becoming dirty by a gap between said portion and the ground both extending tubes 5 have a straight slot 51 for pin 19 to pass through so that extending tubes are confined to move back and forth in parallel tubes 11 and pin holes 54 for pins 55 to pass through for combining with linking tubes 52 having pin holes 56 for pins 55 to insert too linking tubes 52 also have pin holes 57 for pins 53 to pass through for combining with hind leg 4 above mentioned pins 19 53 and 55 must be secured in position without falling off after combining the related parts and must.