PURPOSE: To minimize the moving distance of a tool exchanging device and the storage space by forming a holder unit of numerous holders for holding a column and a tool, and disposing the holders in two rows as well as providing each row with a tool removing/fitting port on the opposite side.

CONSTITUTION: An appropriate number of holder units 4 are removably fixed to a base part 3. Each holder unit 4 is provided with two rows of holders 6 vertically disposed at specified spaces apart on the lateral sides of a column 4a. The column 4a is provided at each holder part with a deformable recessed part 10 formed to insert a tool so as to insert/remove the tool elastically. The base part 3 is provided with a rail 11 so as to guide the travel of a conveyor device 12, and a tool exchanging device 16 is elevated by an elevating device 17. The tool exchanging device 16 is also rotated horizontally by a rotating drive unit. Accordingly, at the time of removing/fitting the tool from/to the holders 6, the conveyor device 12 can move in the shortest distance, and a large number of holders 6 can be accommodated in a small space.