This paper experimentally analyzes the cognition of height of interior-spaces. Subjects experience the experimental space and the compared spaces, and judge which space height is higher than the others. The result shows that the differential limen of height has + - 2 degree accuracy by visual angle to the edge of wall and ceiling. When the difference of the area is 20% or less, the difference of two areas will hardly be sensed, and the height of wider space is felt lower.
