A container for mixing two fluids includes: a container, a pouring cylinder; an upward facing step portion, a cap whose inner circumferential surface is screwed onto an outer circumferential surface of the pouring cylinder, a small container placed on an inner side of the cap; a cuttable first sheet that forms a bottom surface of the small container, a removable cylinder provided at a bottom end of the cap and interposed between the cap and the upward facing step portion, and a first cutter that is provided on the container so as to face a bottom surface of the small container that is placed on the inner side of the cap. The small container is made to approach the first container, and the first sheet is then cut by the first cutter.