To provide an array pitch converter which is compact and can omit a fixed support guide arranged so as to match the maximum length of a connection pantograph mechanism, and an array pitch conversion method.

Grippers 17 for gripping reinforced bar materials are respectively mounted on respective connection hinge sections 14 of the connection pantograph mechanism 12b formed by connecting a plurality of pantograph mechanisms PNT made of diamond-shaped members. An array pitch of the plurality of reinforced bar materials are collectively converted by expanding and contracting the connection pantograph mechanism 12b. Connection pantograph mechanisms 11a, 12a as support members for supporting and reinforcing the connection pantograph mechanism 12b are arranged in parallel in the connection direction. The connection pantograph mechanisms 11a, 12a expand and contract in a body by matching to expansion and contraction of the connection pantograph mechanism 12b within an expansion and contraction length of the connection pantograph mechanism 12b.