NOVELTY - A positioning device comprises a battery box (10) having a first connection base (21) and a second connection base (12) on two ends, the first connection base having a first positioning portion (13) which includes a positioning member (14) or a positioning recess, and the second connection base having a second positioning portion (16); a first fixing base (20) to be electrically connected to electric bicycle and having a reception space in which first connection base is received; and a second fixing base (30) located at one end of second connection base.    USE - Device for positioning the battery box to electric bike.    ADVANTAGE - The battery box is easily installed between the first and second fixing bases which are conveniently connected to desired portions of the electric bicycle. The installation and removal of the battery box do not need any tools and the any user can handle it.    DETAILED DESCRIPTION - A positioning device comprises:    (A) a battery box (10) having a first connection base (21) and a second connection base (12) on two ends, the first connection base having a first positioning portion (13) which includes a positioning member (14) or a positioning recess, the second connection base having a second positioning portion (16);    (B) a first fixing base (20) adapted to be electrically connected to an electric bicycle and having a reception space in which the first connection base is received, the third positioning portion located corresponding to the first positioning portion and including a positioning recess or a positioning member, the first and third positioning portions are engaged with each other, the first connection base being pivotable relative to the first fixing base; and    (C) a second fixing base (30) adapted to be connected to the electric bicycle and located at one end of the second connection base, the second fixing base located in opposite to the first fixing base, the second fixing base having a fourth positioning portion and located corresponding to the second positioning portion, the second and fourth positioning portions being connected to each other.    DESCRIPTION OF DRAWING(S) - The drawing is an exploded view showing the positioning device and the battery box.    Battery box (10)    Second connection base (12)    First positioning portion (13)    Positioning member (14)    Second positioning portion (16)    First fixing base (20)    First connection base (21)    Second fixing base (30)