An internal surface electron beam-irradiating device sterilizes the internal surface of a vial by irradiation with an electron beam. The internal surface electron beam-irradiating device includes an electron beam generator that generates the electron beam, a vacuum chamber containing the electron beam generator, an output window that emits the electron beam to the outside of the vacuum chamber, and an extension nozzle that guides an electron cloud formed by extending the electron beam emitted from the output window. The extension nozzle includes a leaking section that leaks the electron cloud. The leaking section includes empty portions that discharge part of the electron cloud to the outside, and a component portion that guides the electron cloud into the leaking section.