An image capturing module having a built-in dustproof structure includes an image sensing unit, a housing frame and an actuator structure. The image sensing unit includes a substrate and an image sensing chip disposed on the substrate. The housing frame is disposed on the substrate to surround the image sensing chip. The actuator structure includes a lens holder disposed on the housing frame and a movable lens assembly movably disposed inside the lens holder. More precisely, the lens holder has a first surrounding structure disposed on the inner surrounding surface thereof, and the movable lens assembly has a second surrounding structure disposed on the outer perimeter surface thereof and located above the first surrounding structure, and the first surrounding structure of the lens holder and the second surrounding structure of the movable lens assembly are mated with each other to form the built-in dustproof structure.