Current velocity can be determined by measuring the difference of the sound wave traveling time between two points. The multipaths inverted echo sounder (MIES) [Takeuchi et al., J. Acoust. Soc. Jpn. 49, 543--550 (1993)] was developed in order to apply this method to the measurement of the volume transport of the Kuroshio. Measurement of mean current velocity can be made with a difference of reciprocal travel times of the sound wave along two sides of a triangle in a vertical plane, which is constructed by the acoustic paths with a base side of the mooring distance when two multipath inverted echosounders were deployed 10 km apart. The measurement of volume transport was attempted by applying the above method, where three multipath inverted echosounders were deployed so as to construct a regular triangle on the sea bottom. In this paper, the result of the measurement of the volume transport of the Kuroshio over Izu Ridge from 20 March to 25 April 1995 is presented.