Provided is a foldable tote box that enables the content thereof to be visible when the lid is closed. The foldable tote box according to the present invention has a box body that is provided with: a square or rectangular bottom surface part; front, rear, right, and left lateral wall parts that correspond to the respective sides of the bottom surface part; a lid that is configured to extend from the top edge of the rear lateral wall part; and a reinforcement plate for reinforcing the bottom surface part. The reinforcement plate is mounted turnably with respect to a lower edge of the front or rear lateral wall part. The right and left lateral wall parts can be folded inward when the central portion of the bottom surface part is pulled upward. Each of the lateral wall parts is formed from: a frame member for defining the outline thereof and maintaining the shape; and a sheet material that is supported by the frame member. The sheet material has a transparent portion allowing the content of the tote box to be visible from the outside.