A component mounting positional deviation amount measurement unit is set in a feeder setting section of a component mounting machine so as to be exchangeable with a cassette-type feeder, and includes measurement nozzle placement sections in which measurement nozzles exchangeably held in a mounting head of the component mounting machine are placed; measurement component placement sections in which measurement components are placed; and a measurement mounting table on which a measurement fiducial mark is provided. When a component mounting positional deviation amount of the component mounting machine is measured, the measurement component is sucked by the measurement nozzle by holding the measurement nozzle in the mounting head, the measurement component is mounted on the measurement mounting table, and a deviation amount of a mounting position of the measurement component with respect to the measurement fiducial mark is measured as a component mounting positional deviation amount of the component mounting machine.