A plurality of vessel holder means 14 are mounted around a revolving body 12 at an equal circumferential spacing. Each vessel holder means 14 includes two holders 26, 26 for carrying two vessels 4, 4 in vertical alignment. A path along which the revolving body 12 revolves contains an inversion interval C-D and an upright transfer interval D-B and A-C. Inversion means 16 which inverts the vessel holder means 14 about a tangential axis O1 is located within the inversion interval C-D while an electron beam irradiator 24 is located within the upright transfer interval A-C. Vessels which are fed at a vessel feed position A and carried by the holders 26 are subject to the irradiation of the electron beam at an electron beam irradiation position E, then inverted, and when it reaches the electron beam irradiation position E again, the opposite surface is subject to the irradiation of the electron beam. Vessels 4 are inverted again and then discharged at a vessel discharge position B. Using a single electron beam irradiator 24, the entire surface of the vessel 4 being conveyed can be sterilized by irradiation of the electron beam.