PURPOSE: To provide a centering type four-way chucking mechanism capable of the chucking by the correct centering to the center position relative to the table even for a deformed work.

CONSTITUTION: A centering type four-way chucking mechanism where a work 3 is chucked at the center position by four chucking jaws 2 which are orthogonally arranged on a table 1 is provided with four chucking jaws which are arranged in an orthogonal manner to each other with reference to the center of the table and guided and supported in the orthogonally axial direction individually through a straight-advancing guide. Two sets of groove cams 7, 8 which are arranged in a pivotably crossed manner at the center position so as to open/close the chucking jaws in an interlocking manner for each set where two opposite jaws are made one set, and an actuator lever 12 which is swayably connected to the tip of an output shaft of a driving cylinder 10 and simultaneously turns the representative groove cams across two sets of the groove cams are provided.