An information projecting method of projecting information concerning a cut piece, which is cut and separated from a plate-like work and is on a placement table (7, 9), onto the cut piece, comprising: adjusting an aspect ratio of a projector to a material ratio of a long side of the work to a short side of the work by: assigning the long side of the work to a horizontal extension of the aspect ratio of the projector which is aligned in an X-axis direction; and assigning the short side of the work to a vertical extension of the aspect ratio of the projector which is aligned in an Y-axis direction; positionally adjusting the projector and keeping the projector in the adjusted state, wherein a positional relationship between the projector and a predetermined position of the placement table (7, 9) in the X-axis direction, a positional relationship between the projector and the predetermined position of the placement table (7, 9) in the Y-axis direction and a positional relationship between a top face of the placement table (7, 9) and the projector in a Z-axis direction are fixed; finding a positional relationship between a top face of the work and the projector according to a plate thickness of the work and/or a number of stacked cut pieces on the placement table (7, 9), the placement table (7, 9) being positioned at the predetermined position; obtaining an enlargement factor according to the found positional relationship; obtaining an Y-direction image shift according to the enlargement factor; and projecting the information concerning the cut piece onto the cut piece with the enlargement factor and the Y-direction image shift. adjusting an aspect ratio of a projector to a material ratio of a long side of the work to a short side of the work by: assigning the long side of the work to a horizontal extension of the aspect ratio of the projector which is aligned in an X-axis direction; and assigning the short side of the work to a vertical extension of the aspect ratio of the projector which is aligned in an Y-axis direction; assigning the long side of the work to a horizontal extension of the aspect ratio of the projector which is aligned in an X-axis direction; and assigning the short side of the work to a vertical extension of the aspect ratio of the projector which is aligned in an Y-axis direction; positionally adjusting the projector and keeping the projector in the adjusted state, wherein a positional relationship between the projector and a predetermined position of the placement table (7, 9) in the X-axis direction, a positional relationship between the projector and the predetermined position of the placement table (7, 9) in the Y-axis direction and a positional relationship between a top face of the placement table (7, 9) and the projector in a Z-axis direction are fixed; finding a positional relationship between a top face of the work and the projector according to a plate thickness of the work and/or a number of stacked cut pieces on the placement table (7, 9), the placement table (7, 9) being positioned at the predetermined position; obtaining an enlargement factor according to the found positional relationship; obtaining an Y-direction image shift according to the enlargement factor; and projecting the information concerning the cut piece onto the cut piece with the enlargement factor and the Y-direction image shift.