Provided is an optical system which can adjust, including increase, a spin polarization degree of an electron beam. Disclosed is a charged particle device having a charged particle source which generates charged particles, a sample table on which a sample is placed, and a transport optical system which is disposed between the charged particle source and the sample table and transports the charged particles as charged particle flux toward the sample table. In this device, the transport optical system includes a magnetic field generating section which generates a magnetic field having a vertical component to a course of the charged particle flux, an electric field generating section which generates an electric field having a vertical component to the course of the charged particle flux, and a shielding section which shields at least a part of the charged particle flux passed through the magnetic field generating section and the electric field generating section. Moreover, the vertical component of the magnetic field has a magnetic field gradient, and the vertical component of the electric field gives an electrostatic force in a direction opposite to a Lorentz force received by the charged particle flux.