Injector (1, 101, 201, 301) for injecting at least one substance into birds' eggs, said injector (1, 101, 201, 301) comprising: - an injection body (2, 102, 202, 302) intended to be mounted on a support in a vertically moveable manner between a raised position and an injection position, said body (2, 102, 202, 302) being equipped with an injection conduit comprising an inlet for the supply of at least one substance to be injected, - an injection needle mounted on said body (2, 102, 202, 302) and communicating with said injection conduit, and - a guiding and protection tube for the guiding and protection of said needle, mounted in a moveable manner on said injection body (2, 102, 202, 302) between a retracted position wherein the needle is projecting with respect to the distal end of said tube, and an idle position wherein said tube surrounds at least the distal part of the needle, said tube being subject to elastic stress by elastic means towards its idle position and being capable of being moved to its retracted position by pressing its distal end against an egg when the injector is in the injection position, - control means (6, 106, 206, 306) for controlling the supply of said injection conduit with at least one substance, characterized in that: - said guiding and protection tube cooperates with said control means (6, 10, 206, 306) 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; - said control means comprise a supply circuit for supplying substance to said injection conduit, the guiding and protection tube being capable of closing said supply circuit in its idle position; and - said injection body comprises a lower tubular part in the inner passage whereof the guiding and protection tube is mounted in a sliding manner, said supply circuit comprises a first channel, intended to be connected by an inlet to a dispensing system of substance to be injected, which opens via an outlet into the inner passage, and a second channel opening via an inlet into said inner passage and connected by an outlet to the injection conduit, said tube being capable of closing in its idle position the outlet of the first channel and connecting the first channel and the second channel in its retracted position. - an injection body (2, 102, 202, 302) intended to be mounted on a support in a vertically moveable manner between a raised position and an injection position, said body (2, 102, 202, 302) being equipped with an injection conduit comprising an inlet for the supply of at least one substance to be injected, - an injection needle mounted on said body (2, 102, 202, 302) and communicating with said injection conduit, and - a guiding and protection tube for the guiding and protection of said needle, mounted in a moveable manner on said injection body (2, 102, 202, 302) between a retracted position wherein the needle is projecting with respect to the distal end of said tube, and an idle position wherein said tube surrounds at least the distal part of the needle, said tube being subject to elastic stress by elastic means towards its idle position and being capable of being moved to its retracted position by pressing its distal end against an egg when the injector is in the injection position, - control means (6, 106, 206, 306) for controlling the supply of said injection conduit with at least one substance, characterized in that: - said guiding and protection tube cooperates with said control means (6, 10, 206, 306) 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; - said control means comprise a supply circuit for supplying substance to said injection conduit, the guiding and protection tube being capable of closing said supply circuit in its idle position; and - said injection body comprises a lower tubular part in the inner passage whereof the guiding and protection tube is mounted in a sliding manner, said supply circuit comprises a first channel, intended to be connected by an inlet to a dispensing system of substance to be injected, which opens via an outlet into the inner passage, and a second channel opening via an inlet into said inner passage and connected by an outlet to the injection conduit, said tube being capable of closing in its idle position the outlet of the first channel and connecting the first channel and the second channel in its retracted position. - said guiding and protection tube cooperates with said control means (6, 10, 206, 306) 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; - said control means comprise a supply circuit for supplying substance to said injection conduit, the guiding and protection tube being capable of closing said supply circuit in its idle position; and - said injection body comprises a lower tubular part in the inner passage whereof the guiding and protection tube is mounted in a sliding manner, said supply circuit comprises a first channel, intended to be connected by an inlet to a dispensing system of substance to be injected, which opens via an outlet into the inner passage, and a second channel opening via an inlet into said inner passage and connected by an outlet to the injection conduit, said tube being capable of closing in its idle position the outlet of the first channel and connecting the first channel and the second channel in its retracted position.