To provide a sodium hypochlorite injection apparatus which in spite of being simple in structure can prevent irregular variation of the amount of sodium hypochlorite injected and can therefore perform the injection of sodium hypochlorite into an injection site with good accuracy.

A sodium hypochlorite injection apparatus 1 includes a tank 2 for storing sodium hypochlorite, a pump 3 which sucks sodium hypochlorite from the tank 2 and delivers it, and a transport pipe 4 which is connected to the delivery port 3b of the pump 3, transports the sodium hypochlorite to an injection site, and releases it. The relationship between the inside diameter D of the delivery port 3b of the pump 3 and the inside diameter d of the transport pipe 4 satisfy the requirement of formula (1): 0.25D≤d<D.