Chlorine injection concentration management device, chlorine injection concentration management method, and chlorine injection concentration management program

Provided is a chlorine injection concentration management device which makes it possible to align a residual chlorine concentration at a condenser intake port to a target value without necessitating a complicated procedure, as compared to the prior art. A chlorine injection concentration management device 1 for a seawater utilization plant, the device comprising: a data acquisition unit 111 that acquires data of a set including an injection rate of chlorine being injected in from a chlorine injection port in the seawater utilization plant, and the residual chlorine concentration after a predetermined length of time following injection, the residual chlorine concentration being at an inlet port of a condenser that is installed in the seawater utilization plant; a relationship computation unit 112 that takes an exponential approximation of the relationship between the injection rate and the residual chlorine concentration on the basis of data for at least two sets of the injection rate and the residual chlorine