To provide a method and an apparatus, for the measurement of a dimension, where the dimension of a work can be measured with high accuracy and at a low cost.

In the measuring apparatus 10, measurement spheres 28 are installed at the inside of nozzles 22B. The measuring spheres 28 protrude from the tip openings of the nozzles 22B to come into contact with the work 24. At this times, the gaps between the measuring spheres 28 and inside walls of the nozzles 22B are different according to the dimension of the work 24. An A/E converter 18 measures back pressure, when compressed air is supplied to the nozzles 22B. A control part 20 compares this detected value with the reference value of a master, to convert it into the outer dimension of the work 24.