Newcastle disease (ND) is a major threat to poultry, but the outbreak of the disease is well controlled by the vaccination. Recently, in ovo administration technology has been realized as a safe, efficacious, and convenient method for chicken vaccination. However, no in ovo administration has been applied for ND or other live vaccines that are highly pathogenic against chicken embryos. We found that an attenuated Newcastle disease virus (NDV) was applicable for an in ovo vaccination by adsorbing the virus to aluminum hydroxide (AH). Pathogenicity to chicken embryos of the AH-adsorbed NDV could be decreased compared with the administration of the virus alone. Namely, in ovo administration of the AH-adsorbed attenuated NDV resulted in improved hatchability and survival rate and better antibody responses of protection-level immunity compared with the administration of NDV alone. However, further improvements in hatchability and survival rate are necessary for practical application. From these results, in ovo vaccination with the AH-adsorbed attenuated NDV was revealed to be safe and immunogenic to chicken embryos. The use of AH-adsorbed attenuated live viruses might be applicable for in ovo vaccinations against not only ND but also other avian infectious diseases.