An optical touch apparatus includes a light source capable of emitting a beam, a light guide unit disposed in a transmission path of the beam, and an optical detector. The light guide unit includes a light guide body having a first surface, a second surface, a third surface, a fourth surface, and a scattering structure disposed on at least one of the second surface, the third surface, and the fourth surface. The beam is capable of entering the light guide body, being scattered to the first surface by the scattering structure, and then being transmitted to a sensing space. The scattering structure includes separated scattering patterns including a resin composition and scattering particles dispersed in the resin composition. The ratio of the weight percentage of the scattering particles to the weight percentage of the resin composition is equal to or greater than 0.1.