A gradient liquid feed device allows reduction in size of a high performance liquid chromatography type sample analyzer. The gradient liquid feed device includes a plurality of carrier liquid reservoir tanks (51,52) configured to store carrier liquids of mutually different compositions, a plurality of single plunger pumps (1,2) capable of drawing and discharging the carrier liquid from the plurality of carrier liquid reservoir tanks, a mixer (3) configured to mix the carrier liquids discharged from the plurality of liquid feed pumps and feed the mixed carrier liquid, and a pulse damper (4) in communication with the mixer and configured to absorb pulsation that may occur during liquid feeding. The single plunger pumps (1,2) have a function for variably setting a length of stroke for drawing and discharging the carrier liquid and a function for variably setting a ratio between the carrier liquid drawing time and the carrier liquid discharge time.