To make a triangular display in an instant without assembly operation.

A recessed shape is provided at a part of each of a glass 1 and a glass 2, and a red liquid crystal triangular display 3 is provided in a space part formed by joining the glass 1 and glass 2. Stabilizing liquid 5 is put to prevent the damage of the triangular red liquid crystal display 3 installed in the space part of the joined glass 1 and glass 2. A triangular liquid crystal display automobile rear window device is thereby installed at a rear window of an automobile, and the triangular liquid crystal display is made only by switch operation.