PROBLEM TO BE SOLVED: To provide a compound having high harmful arthropod-controlling activity, and to provide a pest-controlling agent comprising the compound. SOLUTION: This compound is an 1,2,4-thiadiazole compound of general formula (1) [wherein, R<1> is a (halogen-substituted) 3-7C alkynyl R<2> is a halogen atom or the like and A is an oxygen atom, sulfur atom, single bond or the like]. The other objective harmful arthropod-controlling agent is characterized by comprising the above compound as the active ingredient.