A working machine comprising: a support member ; a turn member ; a pin inserted to both of the support member and the turn member to turnably support the turn member on the support member ; a flange fixed to the pin ; a collar inserted to an insertion hole formed in the flange ; a retainer bolt inserted to the collar and attached by being screwed to the turn member or the support member ; a contact portion included in the flange ; and a regulator included in the support member , wherein the regulator contacts to the contact portion with a clearance (S4, S5) kept between the collar and an inner circumference surface of the insertion hole , thereby regulating turning of the flange around the pin , the contact portion includes: a first contact portion provided in the flange on a side in a first turn direction around the pin ; and a second contact portion provided in the flange on a side in a second turn direction around the pin , the regulator includes: a first portion to which the first contact portion contact; and a second portion to which the second contact portion contact, and a clearance (S1) between the inner circumference surface of the insertion hole and an outer circumference surface of the collar is larger than a clearance (S2) between the first contact portion and the first portion and larger than a clearance (S3) between the second contact portion and the second portion under a condition where a center of the insertion hole coincides with a center of the collar . a support member ; a turn member ; a pin inserted to both of the support member and the turn member to turnably support the turn member on the support member ; a flange fixed to the pin ; a collar inserted to an insertion hole formed in the flange ; a retainer bolt inserted to the collar and attached by being screwed to the turn member or the support member ; a contact portion included in the flange ; and a regulator included in the support member , wherein the regulator contacts to the contact portion with a clearance (S4, S5) kept between the collar and an inner circumference surface of the insertion hole , thereby regulating turning of the flange around the pin , the contact portion includes: a first contact portion provided in the flange on a side in a first turn direction around the pin ; and a second contact portion provided in the flange on a side in a second turn direction around the pin , a first contact portion provided in the flange on a side in a first turn direction around the pin ; and a second contact portion provided in the flange on a side in a second turn direction around the pin , the regulator includes: a first portion to which the first contact portion contact; and a second portion to which the second contact portion contact, and a first portion to which the first contact portion contact; and a second portion to which the second contact portion contact, and a clearance (S1) between the inner circumference surface of the insertion hole and an outer circumference surface of the collar is larger than a clearance (S2) between the first contact portion and the first portion and larger than a clearance (S3) between the second contact portion and the second portion under a condition where a center of the insertion hole coincides with a center of the collar . <EOS>