PROBLEM TO BE SOLVED: To provide a chemical spraying device that can realize a simple and inexpensive fixing structure of a chemical tank.SOLUTION: A boom sprayer 1 comprises: a chemical tank 2 a lower frame 20 that is arranged under the chemical tank 2 and supports the chemical tank 2 and a holding frame 60 that includes central inclined parts 61c extending along external surfaces of the chemical tank 2 and of which both ends are fixed to a front frame 30 and a rear frame 40 connected to the lower frame 20. The chemical tank 2 is fixed by being arranged between the lower frame 20 and the holding frame 60.