PROBLEM TO BE SOLVED: To provide a suspended matter analysis method, a suspended matter analysis device using the same and an ultrasonic attenuation spectrum analysis device which automatically and continuously analyze, in real time, a concentration and grain size distribution of suspended matters with the concentration and the grain size distribution thereof simultaneously varying in water.SOLUTION: A suspended matter analysis method obtains a concentration and a grain size distribution function of suspended matters in liquid through the processes to calculate: a sonic speed and a wave length from measurement data using predetermined formulas (a); amplitude of a reference spectrum using a predetermined formula (b); a measurement value of an attenuation coefficient using a predetermined formula (c); an estimation value of the attenuation coefficient using predetermined formulas (d); and a volume percent concentration and the grain size distribution which minimize a dispersion of a deviation between the measur
