It also found that most Japanese oppose the idea.
The Pew Research Centre survey released today comes as the two countries are finalising a revision of their mutual defence guidelines that is expected to expand the scope of Japan's military activities in the region.
The telephone survey of 1,000 Americans and 1,000 Japanese also found a high degree of trust between the two nations.
That's a shift from the animosity that prevailed in the 1980s and 1990s when the two countries were embroiled in trade disputes.