Neutron capture therapy apparatus and nuclear transformation apparatus

An object of the present invention is to provide a neutron capture therapy apparatus which can detect whether or not a position at which a target is irradiated with a charged particle beam is normal. The neutron capture therapy apparatus (lA) includes: an accelerator (10) which emits a charged particle beam (P); a target (T) which is irradiated with the charged particle beam (P)to generate a neutron beam (N); a beam transport path (48) that transports the charged particle beam(P), which is emitted from the accelerator (10), to the target (T); and a current detection portion (60) which detects a current value of the charged particle beam (P). The current detection portion (60) is provided inside the beam transport path (48) along an inner wall (48a) of the beam transport path (48) in a state of being insulated by the inner wall (48a).