A coupling support member including a pair of divided pieces is placed in a coupling part between a vane base end portion of a guide vane and an attachment flange, and the pair of divided pieces are joined to the vane base end portion from both the sides in the vane thickness direction. Linear protrusions are respectively formed on both the sides of the vane base end portion. Grooves engaged with the linear protrusions formed in the vane base end portion are respectively formed in the pair of divided pieces of the coupling support member. Side edges that are located on the vane center side of the pair of divided pieces and extend along the chord direction are formed so as to protrude toward the vane center, and the respective tip ends of the side edges are chamfered. The vane base end portion is held between the pair of divided pieces of the coupling support member, by fastening force that is applied to the pair of divided pieces of the coupling support member from both the sides in the vane thickness direction. Such a trouble that a reinforcement fiber layer in an end portion of a vane made of a composite material separates can be minimized.