An apparatus for calculating the toxicity of a new drug candidate substance comprises: a protein network unit which defines a first connection relationship between a plurality of proteins on the basis of interactions between the plurality of proteins; a drug-protein network unit which, on the basis of actions that each of a plurality of drugs have on the plurality of proteins, defines a second connection relationship that the plurality of drugs have with the plurality of proteins; and an input unit which receives information about a target protein which is the target of the new drug candidate substance. In addition, the apparatus for calculating toxicity further comprises a toxicity calculation unit which, when a peripheral protein connected to the target protein through the first connection relationship is selected from among the plurality of proteins, and a target drug and a peripheral drug respectively connected to the target protein and the peripheral protein through the second connection relationship are selected from among the plurality of drugs, calculates the toxicity of each of the target drug and the peripheral drug.