PROBLEM TO BE SOLVED: To cause a double-chamber type chemical device to be automatically replenished with an appropriate amount of chemical, thereby keeping the concentration of the chemical from decreasing, and holding the chemical concentration of a mist of sprayed chemical constant.SOLUTION: The chemical spray device (1) includes: a medium solution container (32) for storing a medium solution to which vibration is transmitted; a chemical storage cup (33) positioned in the medium solution container for storing chemical; a vibration generator (31) for transmitting ultrasonic vibration to the chemical in the chemical storage cup via the medium solution to atomize the chemical; and a chemical supply means (22) for automatically replenishing the chemical in an amount expected to be used. In this way, the time that the chemical in the cup receives the ultrasonic vibration before being atomized is reduced to keep the concentration of the chemical from decreasing and to hold the concentration of chemical components in the sprayed mist constant at a high level.