PURPOSE: To enable the observation and non-observation of the inside of a bathroom as required by incorporating a dimming glass, in which visible-light transmittance is changed by the on-off of supply voltage, into a wall panel.

CONSTITUTION: A light control glass 10, in which a liquid crystal sheet is held between two glass sheets, is mounted integrally to an aluminum sash. The aluminum sash and a framework are connected and fixed to a wall panel 4 by screws, etc. When the state of hot-water supply to a bathtub is confirmed, supply voltage is applied to the light control glass 10. The inside of a bathroom unit 1 is observed from the outside the liqht control glass by transmitting light through the light control glass. When privacy in the bathroom unit 1 is desired to be protected, on the other hand, supply voltage is interrupted, and the light control glass 10 is brought to an opaque state.