The invention provides a charged particle beam-irradiating apparatus (4) capable of obtaining a clear image of the aperture (8c) of a multi-leaf collimator (8). The charged particle beam-irradiating apparatus (4) comprises: a scatterer (6) and ridge filter (7) that irradiate a charged particle beam (P) supplied from a cyclotron (5) on a cancerous area (B) in the body of a patient (A) and a multi-leaf collimator (8) that sets the irradiation bounds of the charged particle beam (P) according to the shape of the cancerous area (B). A collimator shape-confirming unit (9), which is advancible and retractable on the irradiation axis (Q) of the charged particle beam (P), is disposed between the ridge filter (7) and the multi-leaf collimator (8). The collimator shape-confirming unit (9) comprises an image pickup camera (11) that directly images the aperture (8c) of the multi-leaf collimator (8), and is movable between an imaging position that corresponds to the irradiation region (R) comprising the irradiation axis (Q) of the charged particle beam (P) and a standby position at a distance from the irradiation region (R) comprising the irradiation axis (Q) of the charged particle beam (P).Linvention concerne un appareil dirradiation par un faisceau de particules chargées (4) permettant dobtenir une image nette de louverture (8c) dun collimateur multi-feuilles (8). Lappareil dirradiation par un faisceau de particules chargées (4) comprend : un diffuseur (6) et un filtre en peigne (7) qui irradient un faisceau de particules chargées (P) produit par un cyclotron (5) sur une zone cancéreuse (B) dans le corps dun patient (A) et un collimateur multi-feuilles (8) qui établit les bornes de lirradiation au faisceau de particules chargées (P) en fonction de la forme de la zone cancéreuse (B). Une unité confirmant la forme du collimateur (9), qui peut être avancée et reculée sur laxe dirradiation (Q) du faisceau de particules chargées (P) est placée entre le filtre en peigne (7) et le
