1. A compound property prediction apparatus comprising: a training sample library in which a parameter value relating to a chemical structure and a value of a prediction item are preregistered for each individual one of a plurality of training samples; an input device which takes data concerning an unknown sample as input; a parameter generating device which calculates a parameter value of said unknown sample, based on said input data; a similarity calculation device which, based on said parameter value, calculates the degree of similarity between said unknown sample and said individual one training sample; a sub-sample set construction device which constructs a sub-sample set by extracting training samples whose degree of similarity to said unknown sample is not smaller than a predetermined threshold value; a prediction model construction device which constructs a prediction model by performing data analysis on said sub-sample set; and a prediction value calculation device which calculates the value for said prediction item by applying said constructed prediction model to said unknown sample.