The parties include the Democratic Party, the Japanese Communist Party and the Japan Innovation Party, public broadcaster NHK reported.
They said the laws allowing Japan to exercise its right to collective self-defence cannot be approved as they clearly violate the constitution.
Democrat Yoshiaki Takaki said they hope to put the bills up for debate soon and promote nationwide discussions. The parties aim to make the laws’ validity a focus in campaigning for an Upper House election.
The laws are scheduled to take effect on March 29. (IANS)