A guide device for loading a solid matter into a bag including: an upper hopper which performs a reciprocating swinging motion along the conveying direction of the bag and about a supporting shaft located in the center of the upper portion of the upper hoppers, and a lower hopper which is positioned beneath the upper hopper and performs a reciprocating horizontal motion along the conveying direction of the bags and also moved toward and away from the upper hopper. The upper hopper's swing motion and the lower hopper's horizontal motion along the conveying direction of the bag are made in synchronization with the movement of the bag, and the lower hopper is lowered so that its lower opening is inserted into the mouth of the bag.