A flowmeter can measure a small flow rate of fluid with high measurement precision, can be made small-sized, can deal with a variety of types of chemicals, and can be produced easily at a low cost. The flowmeter including: a casing having an enlarged portion and disposed vertically; a float, enclosed in the enlarged portion of the casing and at least partly having a detection surface, which is to be pushed up by a fluid flowing from below into the casing and flowing upwardly in the casing; and at least one displacement sensor, disposed outside the enlarged portion of the casing, for detecting an axial displacement of the float by magnetizing the detection surface of the float.