Abstract: This invention relates to a photomultiplier for detecting the incident position of a plane of incidence, where a weak light beam is reached and to a photomultiplier having a structure for minimizing crosstalk near the incident position of the weak light beam to improve the precision of the position resolving power. Particularly, the anode of this photomultiplier, which extracts the incident position of the incident weak light as an electrical signal, is constituted by a first anode component for detecting the incident position of the incident plane in the X direction and a second anode component for detecting the incident position of the incident plane in the Y direction. The first and second anode components have flat surfaces. These flat surfaces cause the first and second anode components to capture secondary electrons emitted from a dynode in correspondence with the incident position of the weak light beam, at a position closer to the emission position.