Provided are a filled syringe and a method for storing a resin composition, which can suppress generation of a void between the resin composition and an inner surface of the syringe. A filled syringe 1 includes a syringe 10, a plunger 20, and a resin composition 30. When a longitudinal direction of the syringe 10 is a vertical direction and the plunger 20 is above the resin composition 30, a ratio of a cross-sectional area 25 of the plunger at a position of a liquid level 31 at top of the resin composition to a cross-sectional area 35 enclosed by an inner surface 11 of the syringe at the same position as the liquid level 31 at the top of the resin composition is 95% or less.
