＜要　旨＞
We examine the relationship between government expenditure and growth in an R&D-based endogenous growth model in which the R&D abilities of agents are heterogeneous. We analytically demonstrate that if the distribution of ability has a long and fat tail, the relationship between government expenditure and growth becomes nonlinear; the relationship is strong when the size of government expenditure is small enough or large enough, whereas the opposite outcome holds for the moderate size of government expenditure. Our numerical example shows that this nonlinear relationship between government expenditure and growth holds under plausible parameter values.