PURPOSE: To improve efficiency of working at the time of the working of a screw type pump for an engine supercharger, by setting two housings on a drilling machine turntable at point object position relationships, and conducting working on male and female rotor holes alternately and simultaneously.

CONSTITUTION: A turntable 2 is indexed at an origin position, and two housings (a) are set on the table at point object position relationships. Next, a spindle head is descended while a male rotor hole working tool 101 and a female rotor hole working tool 102 are rotated, and the working of the male rotor hole (b) of one housing (a) that is located right under the tool 101 and the working of the female rotor hole (b) of the other housing (a) that is located right under the tool 102, are conducted by means of the tool 101 and the tool 102. After workings, the turntable 2 is turned by 180 degrees with the spindle head in a condition of being ascended, and the female rotor hole (c) of one housing (a) and the male rotor hole (b) of the other housing (a) are simultaneously worked on by means of the tool 102 and the tool 101.