Method for spraying chemical solution

A chemical solution spraying method for spraying a chemical solution onto a canvas forming a loop shape by engaging with a plurality of cylindrical dryer rolls while reciprocating two nozzle devices at the same speed along a rail extending in a width direction of the canvas with respect to the canvas in a dry part of a paper-making machine, wherein the canvas is guided by the dryer rolls with the canvas contacting wet paper, and is then guided by a canvas roll with the canvas separating from the wet paper, a time period Tc during which the canvas is in contact with the wet paper is 0.03 to 5 seconds, a distance the canvas travels in the time period Tc is 0.5 to 16 m, a time period Tn required for each of the nozzle devices to one-way move is 0.5 to 10 minutes, a traveling speed Vp of the canvas is 500 to 1800 m/min, a length K of the canvas is 20 to 80 m, a number of times of contact N of any point on a surface of the canvas with the wet paper during the time period Tn, the time period Tn, the traveling speed Vp, and the length K satisfy a relationship of N=(Tn−Vp)/K, and the number of times of contact N is 20 to 80, and a spray amount of the chemical solution is 0.1 to 500 mg/m2 as an effective component amount that is a total amount of components other than water in the chemical solution, an air permeability of the canvas is 2000 to 50000 cm3/cm2·min, the canvas roll includes an outside canvas roll positioned outside of the canvas loop and an inside canvas roll positioned inside of the canvas loop, and the nozzle device sprays the chemical solution onto the canvas in a time period elapsed until the canvas contacts the outside canvas roll after separating from the wet paper.