PROBLEM TO BE SOLVED: To easily suppress sinking of a plant protection unit.SOLUTION: In a plant protection unit 30, a plate material 40 is laid on a planting base 20, a projection part 46 projecting from a lower surface 40A is inserted to the planting base 20, and a plant protection plate 50 is supported by the plate material 40. Thus, the plate material 40 suppresses sinking of the plant protection unit 30 by dispersing load even if repeatedly receiving load.