Abstract: A semantic data processing apparatus for retrieving one or a plurality of words, having a close meaning to that of an inputted word, in consideration of context or condition, comprises: a communication apparatus 101 for inputting a keyword and context word group; a projective transformation generating module 104 for transforming the inputted keyword and context word group into a keyword vector and a context word vector group indicative of respective meanings, and generating a projector which projects the keyword and a comparison-subjected vector group into a subspace corresponding to the context word group, in a semantic space which is generated in correspondence with a predetermined space generation word, on the basis of the obtained context word vector group; an input/output apparatus 102 for inputting a comparison-subjected word group; a comparison-subjected word group mapping module 107 for transforming the inputted comparison-subjected word group into a comparison-subjected vector group indicative of mea