A fat suction and graft syringe having a negative pressure adjustment means , the syringe having a plunger moving forward and rearward by being inserted into a barrel which is empty, and a needle coupled to a forward end of the barrel by a connector, wherein the syringe comprises: the negative pressure adjustment means supplying pressure allowing fat to be suctioned into the barrel by maintaining an inner space between a forward end of the plunger and the forward end of the barrel at a state of negative pressure during the rearward movement of the plunger , characterized in that the negative pressure adjustment means comprises: a multi-level holding plate formed in an inner space between partition walls of the plunger having a cross-shaped structure formed by the partition walls , the multi-level holding plate composed of at least one plate being formed perpendicularly to the partition walls and dividing the inner space between the partition walls into multi-level areas; and a single-surface rotation clip coupled to a side of an entrance of the barrel and having a bent part configured to be rotated only upward, i.e. rearward, and not to be rotated downward, i.e. forward, and hinged rotatably to a rotation clip fixing part , the rotation clip fixing part being open at a first side thereof and closed at a second side thereof, and configured to have a U shape such that the rotation clip fixing part is coupled to the barrel by fitting an inner space of the rotation clip fixing part over a finger support formed on an upper circumference of the barrel . the negative pressure adjustment means supplying pressure allowing fat to be suctioned into the barrel by maintaining an inner space between a forward end of the plunger and the forward end of the barrel at a state of negative pressure during the rearward movement of the plunger , characterized in that the negative pressure adjustment means comprises: a multi-level holding plate formed in an inner space between partition walls of the plunger having a cross-shaped structure formed by the partition walls , the multi-level holding plate composed of at least one plate being formed perpendicularly to the partition walls and dividing the inner space between the partition walls into multi-level areas; and a single-surface rotation clip coupled to a side of an entrance of the barrel and having a bent part configured to be rotated only upward, i.e. rearward, and not to be rotated downward, i.e. forward, and hinged rotatably to a rotation clip fixing part , the rotation clip fixing part being open at a first side thereof and closed at a second side thereof, and configured to have a U shape such that the rotation clip fixing part is coupled to the barrel by fitting an inner space of the rotation clip fixing part over a finger support formed on an upper circumference of the barrel . a multi-level holding plate formed in an inner space between partition walls of the plunger having a cross-shaped structure formed by the partition walls , the multi-level holding plate composed of at least one plate being formed perpendicularly to the partition walls and dividing the inner space between the partition walls into multi-level areas; and a single-surface rotation clip coupled to a side of an entrance of the barrel and having a bent part configured to be rotated only upward, i.e. rearward, and not to be rotated downward, i.e. forward, and hinged rotatably to a rotation clip fixing part , the rotation clip fixing part being open at a first side thereof and closed at a second side thereof, and configured to have a U shape such that the rotation clip fixing part is coupled to the barrel by fitting an inner space of the rotation clip fixing part over a finger support formed on an upper circumference of the barrel . <EOS>