Abstract: A dust seal device of a linear guide apparatus includes a pair of side seals respectively attached to end cap which are in turn attached to opposite ends of a slider main body. Each side seal has an inverted U-shaped and consists of a mandrel formed of a steel plate coated with a synthetic rubber. The side seal includes side groove seal portions formed at both sides of the inner edge of an opening of the side seal and an upper groove seal portion formed at an upper side of the inner edge. Each end cap includes a recessed groove formed in an inner peripheral edge surface of an opening of the end cap so that the recessed groove extends in a U-shape along the inner peripheral edge. The side seal is inserted into the recessed groove from a lower side of the end cap by pushing upwardly so that the side seal is fitted into the recessed groove.