a robot coordinate system setting method is provided which facilitates the setting of a common coordinate system with respect to each of robots in a robot system or a robot installed in substitution for one of the robots . a coordinate transformation matrix for transforming a provisional coordinate system , which a first robot has recognized by accessing a second jig , into a common coordinate system , which the first robot has recognized by accessing a first jig , is calculated , and using this coordinate transformation matrix , a provisional coordinate system which a second robot has recognized by accessing the second jig is transformed into the common coordinate system which is to be recognized by the second robot , and is set with respect to the second robot . if a robot is installed in substitution for the second robot , method similar to the above is used to obtain a second provisional coordinate system , which the substitute robot has recognized by accessing the third jig , and is transformed into the common coordinate system which is to be recognized by the substitute robot , whereby the common coordinate system is set with respect to the substitute robot .