A therapeutic agent for treating a Trypanosoma-associated disease a method of preventing infection by Trypanosoma parasites, or killing Trypanosoma parasites and use thereof, the therapeutic agent and the method each using a mechanism different from a mechanism used in conventional technology. The therapeutic agent of the present invention for treating a Trypanosoma-associated disease includes, as a medicinal component, an antisense oligonucleotide suppressing the expression of an inositol 1,4,5-trisphosphate receptor protein of Trypanosoma parasites.
