To provide a focusing ion beam device by which influence of a noise can be remarkably reduced even in high power and an image of high resolution can be obtained.

A scanning signal from a scanning signal generating circuit 7 is supplied to a switch circuit 22, but at observing time of low power, for example, in a range of 100 times to 10 thousand times, the switch circuit 22 is switched to a terminal (a) by control from a control circuit 21. As a result, an ion beam is deflected by electrostatic deflecting systems 6a and 6b, and a two-dimensional area of a sample is scanned. When power is not less than 10 thousand times, the switch circuit 22 is switched to a terminal (b) by control from the control circuit 21. As a result, a deflecting current to two-dimensionally scan the ion beam is supplied to electromagnetic deflecting systems 20a and 20b.