To reduce amount of a material while maintaining load resistant strength against rupture and collapse at collision time required for a support column in an erection structure of the support column of base fixing system and erect the support column to prevent direct collision against a base plate and a bolt and a nut even in a vehicle having small vehicle height.

This base fitting 1 for erecting and holding the support column 2 of a protective fence 3 installed on a road R side on an upper face of a wheel guard T is formed by a support column erection hole 1a in which a lower end side of the support column 2 is internally fitted and a base part 1b fixed on the wheel guard T. Height L1 from the wheel guard T of a road side wall part 7a in a hole wall part 7 of the support column erection hole 1a is set to be small, and height L2 from the wheel guard T of an opposite side wall part 7b is set to be large while fixed on the wheel guard T to prevent direct collision against the base fitting 1 of the vehicle S. A tightening wall part 8 for maintaining load resistant strength against rupture and collapse required for the support column 2 when the vehicle S collides against the protective fence 3 is provided.