PROBLEM TO BE SOLVED: To provide technical means which secures an ultraviolet ray shielding performance of titanium oxide as a plant protective agent, while efficiently reducing harm effects on plant based on its photocatalysis accompanying inevitably to the ultraviolet ray shielding performance. ! SOLUTION: A plant protective agent comprises water as medium and a rutile-type titanium dioxide (TiO2) particle with an average particle diameter of 10 to 200 nm. Particularly preferably, the rutile-type titanium dioxide particle is composed with a transparent ultraviolet reflection agent which does not show any photocatalysis. ! COPYRIGHT: (C)2014,JPO&INPIT