This paper investigates nonlinear effects of government debt on private consumption in 16 OECD countries. The estimated consumption function shows smooth regime switching depending on the debt-to-GDP ratio, and the threshold level of regime switching is found to be the ratio of 83.7 percent. The results reveal that a higher level of government debt crowds out private consumption to a greater extent, and that the degree of the crowding out effect has deteriorated since the global financial crisis.