In a linear guide, a separator is interposed between each pair of adjacent balls. The separator has a separator main body interposed between the adjacent balls, and arm portions provided at end portions of the separator main body, which are arranged in the direction of width of each of rolling element rolling grooves for rolling the balls. The separator also has a guide groove which guides the arm portions of the separator along a circulating direction of the balls when the balls circulate along a passage formed by the first and second rolling element rolling grooves, a direction changing passage, and a rolling element passage.