A novel chitinase, a polynucleotide encoding the same, a vector and a transformant comprising the polynucleotide, an antibody against the chitinase, and a screening method for screening a substance capable of modifying the chitinase, are disclosed. According to the chitinase, polynucleotide, or vector, it is possible, for example, to exterminate ticks, or to treat or prevent tick-borne infections such as piroplasmosis, Q fever, or viral encephalitis.