PROBLEM TO BE SOLVED: To provide a phytotoxic injury reduction method in which, when various agrochemicals are used, the phytotoxic injury imparted to useful plants can effectively be reduced without reducing the activity of the agrochemicals.SOLUTION: The agrochemical phytotoxic injury reduction method is a method for reducing a phytotoxic injury that occurs when agrochemicals are sprayed during the cultivation of useful plants, and in which, characterized, a dry pulverized fine powder seaweed having an average particle size of 1 μm or more and 20 μm or less, or a fluid dispersion containing said fine powder seaweed dispersed therein, is sprayed before, during or after the application of the agrochemicals.SELECTED DRAWING: None