PURPOSE: To prevent a theft of a bicycle, etc., by inserting a fixing rod into a hole formed in a plate linked to a pivot part, and locking one end part of the fixing rod by a locking member so as not to be released from the plate.

CONSTITUTION: The bases of arm elements 3a, 3b of a frame mount arm 3 are pivoted on a plate 9 through pivoting pins 8 so that they can free rise and fall on rising ear parts 9a. A carrier bar is fixed to the plate 9 by a fixing rod 11 of a U-shaped rod, etc., passing and extending through a hole 10a and an oblong hole 10b from below the plate 9 and having screws on both ends. Further, one end part of the fixing rod 11 inserted into the hole 10a of the plate 9 is locked by a locking device 7 so as not to be released from the plate 9. Thus, since a locking nut 12 cannot be turned in state where it is fixed to the frame, etc., of a bicycle, the fixing rod 11 cannot be removed from the plate 9 to prevent a theft.