To provide a method and an apparatus that can evaluate water quality of ultrapure water by detecting an amine-based organic substance or the like contained in the ultrapure water in a short period of time with high accuracy.

In a water quality evaluating method, sample water is passed as an upward flow into a column 4 through a pipe 1, a valve 2 and heating means 3, and particles Si of a silicon material are filled in the column 4, and a flow rate of the upward flow is selected so that the particles Si of the silicon material form a fluidized bed, and water brought into contact with the particles Si of the silicon material is discharged through a pipe 5, a valve 6 and a flowmeter 7, and a portion of the water is dispensed by a pipe 8 branched from the pipe 7, measured for a hydrogen concentration by using a hydrogen concentration meter 9 and then discharged through a flowmeter 10, and water passing velocity into the column 4 is set to SV 100-10,000h^-1.