A turbine flowmeter includes an impeller rotatably provided within a flow passage through which a fluid to be measured flows and comprising a rotary shaft which rotates together with the impeller, a pair of bearing part having bearing surfaces for axially supporting the rotary shaft, a holding part for holding the bearing part and provided on the flow passage, an oil accumulating space defined by an end portion of the rotary shaft and bearing surfaces facing respective sides of the end portion, an oil accumulating part provided on the holding part and filled with the lubricating oil to be supplied to the oil accumulating space, an oil supplying part for supplying oil to the oil accumulating space which part comprises a capillary part connected on one end direct to the oil accumulating part and communicated on the other end to the space, wherein the lubricating oil is supplied to the space via the oil supplying part from the oil accumulating part by capillarity introduced in the oil accumulating part and the space, and wherein the surface tension of the lubricating oil in the space is equal to or larger than the surface tension of the lubricating oil in the oil accumulating part.