PROBLEM TO BE SOLVED: To provide an assistant member-attaching tool enabling the assistant member-attaching tool to be attached to a plate-shaped member for greening so as not to reduce the waterproof properties and the strength of the plate-shaped member for the greening. SOLUTION: The assistant member-attaching tool capable of being attached to a groove part between ribs formed on the outer surface of the plate-shaped member for the greening capable of forming a wall part or a roof, and for attaching an assistant member for growing a plant, allowing the vine of the plant growing along the outer surface of the plate-shaped member for the greening to coil around, includes a fixing part installed between the bottom face of the groove part and an engaging protruded part formed in the rib and attached to the groove part, and an attaching part bound with the fixing part and for attaching the assistant member for growing the plant. COPYRIGHT: (C)2013,JPO&INPIT