A display apparatus for switching between 2-dimensional (2D) and 3-dimensional (3D) image displaying modes is disclosed. In one embodiment, the display apparatus includes: i) a display unit configured to emit light, ii) a first optical sheet configured to input the emitted light and output a first refracted light and iii) a second optical sheet configured to input the first refracted light and selectively output one of a second refracted light and a third refracted light, wherein the first optical sheet is located between the display unit and second optical sheet. The display apparatus further includes an actuator configured to move at least one of the first optical sheet and the second optical sheet between a contacting state and a separating state, wherein the first and second optical sheets contact each other at the contacting state so that the second optical sheet outputs the second refracted light, and wherein the first and second optical sheets are spaced apart from each other at the separating state so that the second optical sheet outputs the third refracted light.