A mass spectrometer that performs ion-molecule reaction ionization and accurately performs qualitativequantitative analysis on a sample containing multi-components for a short time is achieved without an increase in the size of the device. A plurality of link mechanisms connects the bearing rotation member with each one of movable bodies respectively, and rotates the bearing rotation member in accordance with a movement of the movable bodies. The sources of the first and second transistors are connected via an impedance. Light emitted from the optical source is index-match coupled into the cladding by using an index-matched element, and subsequently coupled into the fiber core along its length.