Provided is a chemical storage apparatus including a reservoir including a chemical tank configured to store a chemical, a first fixing member disposed on an upper surface of the chemical tank, and a second fixing member disposed on a lower surface of the chemical tank, a sensor configured to measure a specific parameter of the chemical stored in the reservoir, a receptacle having a space in which the sensor is accommodated, and coupling members for attaching or detaching the receptacle to or from the first fixing member and the second fixing member, respectively.