To provide a cage body improving a workability at a time when the upper space of a place, where a reinforced concrete construction is built, is limited and largely enhancing a quality as reinforced concrete and a method for constructing a pile.

Strands 5 and hoops 3 are bound so that the crossing angle can be changed by using a binding fixture 7 allowing a sleeve 9 holding the strands 5 as axial reinforcements to turn to the sleeve 11 holding the hoop 3, thus forming the cage body 1. A length 4 is shrunk previously by bending a plurality of the strands 5 in an arcuate form while changing the crossing angle with the hoops 3 before the cage body 1 is arranged at a specified place in the cage body 1. The cage body 1 in which the length is shrunk is arranged at the specified place, a plurality of the strands 5 are formed in a linear shape while returning the crossing angle with the hoops 3 to original states and the length of the cage body 1 is elongated.