Abstract: A linear motion guide device provided with a plural ball row chain capable of achieving easy assembling working and realizing an improved smooth ball circulation.It is characterized that ball retainer members 23, 23 to which one sides of the respective two ball rows 3, 3 arranged along loaded ball rolling grooves 10, at a time of removing a movable block 4 from a track rail 1, are formed to the movable block 4, the falling-off of the balls in the ball rows can be prevented by the assembling of the ball retainer members 23, 23 and a plural ball row chain 20, and the hanging-down of an end portion of the plural ball row chain 20 can be also prevented.