POSITIONING MECHANISM

PROBLEM TO BE SOLVED: To perform exact positioning by reducing an influence of friction between an annular frame and a positioning mechanism in the positioning mechanism performing the positioning of the annular frame supporting a workpiece.SOLUTION: In a positioning unit performing the positioning of an annular frame F supporting a workpiece W via an adhesive tape T, an outer circumference of the annular frame F includes 4 positioning reference surfaces F2 to F5. The positioning unit is constituted of fixed blocks 800a and 801a having two rotatable positioning pins 802 and 805, respectively, and movable blocks 800b and 801b which are opposed to the fixed blocks, have one or more rotatable positioning pins 808 and 811 and can advance and retreat in closing and separating directions to/from the fixed blocks. The positioning reference surfaces F2 to F5 of the annular frame F are made to abut on the rotatable positioning pins by moving the annular frame F in a direction coming close to the movable blocks and the fixed blocks and thus positioning of the annular frame F is performed.