An autosampler is provided with a needle that has a capacity to retain a sample therein and has both ends each formed in a pointed shape, a first adapter that has an opening and causes the needle and a syringe pump to be in communication with each other through the insertion of the upper end part of the needle into the opening, and a second adapter that connects the needle and a mobile-phase liquid-delivery flow path using a structure similar to that of the first adapter. The autosampler is configured such that the first adapter and the second adapter are attached to and removed from the upper end part of the needle so as to create flow paths including the needle as necessary and carry out a sampling operation and injecting operation.