1. A gesture detection device, comprising: a detection surface having a normal direction; a first image sensor disposed on the detection surface and capturing a first image along a direction deviating a predetermined angle from the normal direction; a second image sensor disposed on the detection surface offsetting a predetermined distance from the first image sensor along a Z-axis and capturing a second image along a direction deviating a negative predetermined angle from the normal direction; and a processing unit configured to calculate a two-dimensional coordinate according to positions of a pointer image in the first image and a pointer image in the second image, and identify a click event of the Z-axis when a size difference of the pointer images between the first image and the second image is larger than or equal to a difference threshold.