A coordinate measuring instrument including: a table (50) movable in the direction of Y-axis on a bedplate (10); a slider (110) movable in the direction of X-axis through supports (90) and a beam member (100); a Z-axis structure (180) supported by this slider (110) in a manner to be movable in the direction of Z-axis; a probe stocker (290) fixed to the table (50) and capable of resting thereon a plurality of probe holders (250) each having a signal producing probe (280); and a probe mounting-removing mechanism (200) provided in the Z-axis structure (180), the probe mounting-removing mechanism (200) being capable of selectively installing a signal producing probe (250) most suitable for the shape of a work (320) to be measured.