The purpose of this paper is to present a method for measuringthe degree of scale economies in production, i.e. passus coefficient .This method is characterized mainly by the two points. The first isthis method aims to estimate the upper and lower bounds of the passuscoefficient using the non-specified homogeneous production functionin order to avoid the specification error that might otherwise beinvolved(boundary approach). Secondly, it also aims to derive thetwo boundary estimates directly rather than through estimation ofproduction function. This avoids 'multi-collinearity' problem withinput data that is especially troublesome in cross-section analyses(one parametric approach)This method is applied to Japanese manufacturing data andreveals the existence of scale economies in over half of the twodigit industries which are analyzed.