Abstract: A connection device for connecting a bag to a bicycle saddle a first connection unit connected between the saddle frame and the top of the bag, and a second connection unit which is connected between the seat post and the rear end of the bag. The second connection unit uses a clip member to clip on the seat post. The first connection unit includes a first portion connected to the saddle frame and a second portion pivotably connected between the first portion and the bag which can be pivoted upward when the second connection unit is disengaged from the seat post, and the angular position for the bag can be set as needed.