A falling object blocking structure for an entrance of a building is provided to guide rainwater to a drain pipe and to prevent a drain pipe from getting clogged by garbage and to dispose of garbage accumulated on the inside easily. A falling object blocking structure for an entrance of a building comprises a main frame(10) installed to a wall(1) on the upper part of an entrance of a building by a pair of anchor bolts, a horizontal member(20) installed to be inclined forward and to be rotative in the main frame and provided with a vertical filter and an upper filter to filter out water flowing along an inclined lower surface and to guide falling garbage toward the lower surface, a cylindrical water collecting pipe(30) inserted to the upper part of the front frame of the main frame to collect water flowing along the lower surface of the horizontal member and to guide the collected water to a drain pipe(2) installed to an external wall of a building, an opening and closing device installed to the lower part of the main frame to prevent the horizontal member from rotating on a hinge shaft and descending, and a connecting pipe connecting the water collecting pipe of the drain pipe and the water collecting pipe and draining off the collected water to the drain pipe.