Liquid feed pump and liquid chromatography device

A liquid feed pump which sucks or discharges a liquid, comprising:

• a first plunger pump which sucks or discharges the liquid by sliding of a first plunger;
• a second plunger pump which sucks or discharges the liquid by sliding of a second plunger;
• and
• a liquid replacement mechanism which replaces the liquid to be introduced into the liquid feed pump, wherein
• the first plunger pump and the second plunger pump are connected in series in a channel in which the liquid moves,
• the first plunger is structured to be able to move between a first lower limit point and a first upper limit point in the first plunger pump,
• the second plunger is structured to be able to move between a second lower limit point and a second upper limit point in the second plunger pump,
• in the second plunger pump, a second plunger seal for sealing between a main body of the second plunger pump and the second plunger is located at a position nearer to the second lower limit point than to the second upper limit point,
• when the liquid in the liquid feed pump is replaced, the first plunger slides back and forth in a space between the first lower limit point and the first upper limit point, and
• when the liquid in the liquid feed pump is replaced, the second plunger stops at least temporarily at a position nearer to the second upper limit point than to the second lower limit point or slides back and forth for a shorter distance than when the liquid feed pump sucks and discharges the liquid.