A theft proof poster display device having front and back extruded portions pivotally connected to one another to define a frame forming member. The front portion defines a generally u-shaped member having smooth surfaces and rounded non-convoluted corners and the front and back portions are biased together under spring compression rendering a poster frame which cannot be gripped with enough frictional force to open the frame. An opener tool with lever arm and an integral inclined planar wedge member is engageable with the front portion of the frame for opening the poster display device.