A particle beam system is offered which can prevent contamination of the inside of the objective lens, the objective lens being located at the front end of the optical column. The particle beam system has an optical column equipped with a particle beam source for emitting a particle beam and a beam passage pipe through which the beam passes. The system further includes a vacuum chamber connected with the front end portion of the column. The beam passed through the pipe is released from the front end of the column. An inner pipe is detachably disposed inside the beam passage pipe located at the front-end side of the column.