There is described a sterilization apparatus (9) for sterilizing a web (4) of packaging material advancing along a web advancement path (P). The sterilization apparatus (9) comprises an irradiation device (26) for sterilizing the advancing web (4) of packaging material, a main shielding chamber (27) housing the irradiation device (26) and comprising an advancement channel (28) having an inlet opening (29) and an outlet opening (30) and through which, in use, the web (4) of packaging material advances along the sterilization portion (P1), an auxiliary shielding chamber (31) being arranged upstream of the advancement channel (28) along the web advancement path (P), the auxiliary shielding chamber (31) having an inner space (32) being in fluid connection with the advancement channel (28) and comprising an extraction opening (52) configured to allow to extract gas from the auxiliary shielding chamber (31). The sterilization apparatus (9) further comprises an aspiration device configured to generate a first flow of gas within the advancement channel (28) from the outlet opening (30) to the inlet opening (29) and a second flow of gas from the inlet opening (29) to the extraction opening (52).L'invention concerne un appareil de stérilisation (9) pour stériliser une bande (4) de matériau d'emballage avançant le long d'un trajet d'avancement de bande (P). L'appareil de stérilisation (9) comprend un dispositif d'irradiation (26) pour stériliser la bande (4) avançant du matériau d'emballage, une chambre de protection principale (27) logeant le dispositif d'irradiation (26) et comprenant un canal d'avancement (28) ayant une ouverture d'entrée (29) et une ouverture de sortie (30) et à travers lequel, lors de l'utilisation, la bande (4) de matériau d'emballage avance le long de la partie de stérilisation (P1), une chambre de protection auxiliaire (31) étant disposée en amont du canal d'avancement (28) le long du trajet d'avancement de bande (P), la chambre de protection auxiliair
