A glass apparatus for watching a polarized image is provided. The glass apparatus includes a film unit for double-refracting the polarized image when the glass apparatus is tilted; a sensor unit for detecting a slope of the glass apparatus based on a horizontal plane; a voltage driving unit for applying a driving voltage corresponding to the slope detected by the sensor unit, to a liquid crystal cell; the liquid crystal cell for switching an orientation according to the driving voltage, and changing polarization property of an image passing through the film unit according to the switched orientation; and a polarizer for polarizing the image passing through the liquid crystal cell in a preset polarization direction.