It is said that the democratic nations, in general, spend less on arms than their autocratic counterparts. Then, “would there be a propensity on military expenditure as well among democratic nations according to the political system they adopt and the situation they face?” In other words, “would ‘Presidentialism make differences in investing in arms, and if it does, would there be a significant change on the military budgets when the opposition takes the majority?” This is a question that rings. Presidentialism has its own idiosyncratic check and balances-separation of powers-system, if operated correctly. So it may well have a situation where the ruling party takes the government while the opposition holds the parliament at the same time, sacrificing the military budget plan over the domestic power game. Parliamentarianism, on the other hand, is exempted from inter-branch disputes theoretically. The hypothesis is that under presidentialism, a ruling government would have a harder time to pass a larger military budget when the national assembly is held by the opposition. The result of the panel analysis shows that the divided government condition does affect the amount of defense budget negatively as well as some other domestic political conditions under democratic presidentialism.