In a precision machine tool wherein a spindle head that is movable in the up and down direction is disposed on a column disposed on a bed and a water storage space for storing temperature-regulated cooling water is formed inside the column, the column has, in a lower part thereof, intake ports through which cooling water is led into the water storage space, the column has, in an upper part thereof, and an air vent hole through which air in the column is discharged is formed at a position higher than the drain opening.