The NdMnO3/Mn3O4 nanocomposite film was synthesized by spontaneous phase decomposition of NdMn2O5. NdMnO3 is a canted A-type antiferromagnet with a Néel temperature of about 75 K, while Mn3O4 is ferrimagnetic below its Curie temperature of 42 K. Ferromagnetic order of the Nd moments in NdMnO3 around 15 K has been confirmed. These moments are antiferromagnetically coupled with the Mn moments. The effect of the consecutive magnetic orderings of NdMnO3 on the exchange coupling between NdMnO3 and Mn3O4 has been investigated. The temperature dependence of the exchange bias manifests itself as a peak at 20 K, which is explained in terms of competing ferromagnetic and antiferromagnetic coupling of the Mn and Nd magnetic sublattices with Mn moments of Mn3O4, respectively.