Provided is a motion guide device, which includes: a track rail; rolling elements; a moving block, which has an endless circulation path; and a holding belt having pockets, wherein the holding belt has a pair of end portions opposed to each other through intermediation of a free rolling element in the endless circulation path, and wherein a condition of (X−Y)×Z>(B+C)−A>0 is satisfied, where: A represents a path length of the endless circulation path; B represents a total length of the holding belt; C represents a diameter of the free rolling element; X represents a diameter of each of the pockets; Y represents a diameter of each of the rolling elements; and Z represents the number of the rolling elements arrayed in the holding belt.