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 neon tube 4 is put in a space part 3 formed by joining the glass 1 and glass 2. Stabilizing liquid 6 is put to prevent the damage of the red neon tube 4 installed in the space part 3 of the joined glass 1 and glass 2. A triangular neon tube display automobile rear window device is thereby installed at a rear window of an automobile, and a triangular neon tube display is made only by switch operation.