An injector for injecting at least one substance into eggs, comprising an injection body that can be moved between a raised position and an injection position, and equipped with an injection conduit, an injection needle, a guiding and protection tube of the needle subject to elastic stress by elastic means to an idle position and capable of being moved towards a retracted position by pressing its distal end against an egg when the injector is in the injection position. The injector is equipped with control means for controlling the supply of said injection conduit with at least one substance, said tube cooperating with said control means to disable the supply of said injection conduit when said tube is in the idle position and to enable the supply of said conduit when said tube is in the retracted position.