A micro device includes an epitaxial structure and a light guide structure. The epitaxial structure has a top surface. The light guide structure is disposed on the top surface, and the light guide structure includes a connecting portion and a covering portion. The connecting portion is disposed on an edge of the epitaxial structure and extends along a sidewall of the epitaxial structure. The covering portion is disposed on the top surface and connected to the connecting portion. A width of the connecting portion at the edge of the epitaxial structure is smaller than a width away from the top surface.