Japan's new Prime Minister Yoshihiko Noda has named a youthful cabinet lacking the usual political heavyweights, as he attempts to unite a divided party and safeguard a fragile post-quake recovery.

Japan's sixth new leader in five years gave the key posts of Foreign and Finance Ministers to two allies in their 40s, considered young in Japanese politics for such roles.

The position of Finance Minister went to relative unknown Jun Azumi, 49, against expectations Noda would pick a veteran from his ruling Democratic Party of Japan (DPJ) to wrestle with the world's biggest debt burden.

Koichiro Gemba, 47, became Foreign Minister, AFP reported.