To provide an upflow anaerobic treatment method by which ballooning of granules and channeling in the up flow of water to be treated are prevented and the occurrence of a possibility of outflow of the granules entrained by the treated water from a means for discharging the treated water is averted.

The method for supplying the water to be treated of an upflow anaerobic treatment apparatus is characterized in that a means for supplying the water to be treated has discharge nozzles arranged apart prescribed intervals within an anaerobic treating vessel of the upflow anaerobic treatment apparatus and that the velocity of discharge flow of the water to be treated from the discharge nozzles is intermittently specified to 3 to 5 times that in ordinary operation.