Provided are a water toxicity detecting apparatus and a method using sulfur particles. The water toxicity detecting apparatus using sulfur particles includes: a reaction container containing microbes, in which externally-supplied sulfur particles and oxygen are reacted to form sulfate ions by the microbes; a water sample inlet through which a water sample is flown into the reaction container; an air inlet through which an air is flown into the reaction container; a first detection unit which detects pH and electrical conductivity of the inflow water sample flown through the water sample inlet; a second detection unit which detects pH and electrical conductivity of the water sample containing the sulfate ions generated in the reaction container; a central processing unit which stores data of the ph and electrical conductivity of the inflow water sample flown through the water sample inlet, adjusts a pumping speed of a pump provided to the water sample inlet and a flow rate of the air, and compares data of the first detection unit with data of the second detection unit to determine presence of toxicity of the water sample; and an outlet through the after-toxicity-test water sample is exhausted from the reaction container.