A case includes a lid and a case body provided with a traversing aperture. The damper has a tubular section at its end facing the mouthpiece and can be inserted in a sealing manner into the mouthpiece opening. A polarization voltage is applied between the membrane and the electrode. The rotatable member includes a hole therethrough such that when the hole is aligned with the first bore, thermoplastic may travel freely through the first bore. The region and the distal end are disposed so as not to make contact with each other but to be in close proximity to each other so that the liquid held on the outer periphery of the distal end attracts particles desorbed from the sample as a result of irradiation with the laser light.