Provided is a ground reinforcement structure installed on a ground (10) in which a sandy soil layer (11) having a weak surface layer is provided and thus large-caliber excavation is difficult to be performed, the ground reinforcement structure including a ground reinforcement material (100) including: an expansion-type steel pipe (110) inserted to be installed in a small-caliber drilled portion (A) having a diameter of 51 mm to 61 mm and expanded by hydraulic pressure; and a settlement member (120) coupled to a rear end of the expansion-type steel pipe (110). Here, the expansion-type steel pipe (110) is inserted into the sandy soil layer (11), and the settlement member (120) is inserted into a rock layer (12). In this case, the settlement member (120) of the ground reinforcement structure according to the present invention is fixed to the rock layer (12), fixing force is excellent.