A DNA coding for a fusion protein comprising a polypeptide having the antigenicity of Mycoplasma gallisepticum and a polypeptide derived from Herpesvirus outer membrane protein, in which the polypeptide derived from the outer membrane protein has been ligated with the polypeptide having the antigenicity of Mycoplasma gallisepticum at the N terminus thereof, is prepared. The DNA is inserted into a region non-essential to growth of Avipox virus and the resulting recombinant Avipox virus is provided as a more potent recombinant virus as an anti-Mycoplasma vaccine.