The present invention provides a tetrazoyloxime derivative which is less likely to cause chemical injury to useful plants and is also superior in chemical efficacy to a conventional hetero ring-substituted oxime derivative. A tetrazoyloxime derivative represented by the general formula (1): X represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a cyano group, a methanesulfonyl group, a nitro group, a trifluoromethyl group, or an aryl group; A represents a 1-alkyltetrazoyl-5-yl group or a 5-alkyltetrazoyl-1-yl group; and Het represents a pyridyl group having a substituent or a thiazoyl group having a substituent, and a plant disease controlling agent containing the same as an active ingredient are disclosed.