<p>A centering unit of a propeller turn-over apparatus is disclosed. The centering unit is installed in a turn-over apparatus turning over a propeller when the propeller is manufactured and aligning the center of the propeller mounted in the turn-over apparatus. The centering unit comprises: a pair of transfer screws where a thread is formed on an outer circumferential surface; a pair of center alignment members moving in opposite directions from each other along the transfer screws as the transfer screws rotate; a driving source providing a driving force to rotate the transfer screws; and an electrically operated means transmitting the driving force of the driving source to the transfer screws. The center alignment members move in the opposite direction from each other and come in contact with the inner circumferential surface of a penetration hole formed in a boss unit of the propeller so as to perform a centering work of the propeller and to fixate the propeller.</p>
