Provided is a device for unstopping a stopped specimen vessel that contains a liquid specimen including a bio-derived component such as blood, cells, or DNAs, the device being equipped with a mechanism which sucks and captures particles floating around the opening of the specimen vessel and prevents contamination of the specimen. The unstopping device includes a vessel-gripping mechanism which grips a vessel and an unstopping mechanism which grips the stopper of the opening of the vessel, and removes the stopper from the opening of the vessel by changing the relative distance between the vessel-gripping mechanism and the unstopping mechanism. The unstopping device is equipped with: suction holes for sucking therethrough the gas which is present around the opening and contains liquid or solid particles; a pipeline which is connected to the suction holes and through which the sucked gas and particles are led downstream; a suction device connected to the pipeline; and a spirally flexed pipeline part disposed between the pipeline and the suction device.