Filling device for filling capsules of bottom - lid type with products, advantageously solid forms for pharmaceutical, food, or cosmetic use, including: - a feeding conduit that defines a feeding direction and is adapted to slidingly housing a row of products, said feeding conduit including a bottom end portion adapted to slidingly house, below the row of products, a group including one or more products aligned; - a blocking and feeding system for blocking the row of products and feeding each bottom below with one group of products; said blocking and feeding system including a first blocking and feeding element and a second blocking and feeding element; said first blocking and feeding element being movable between an operative position, wherein it closes the feeding conduit and is adapted to support and block a first product of the group, and an inoperative position, wherein the feeding conduit at the bottom end portion is inferiorly open; said second blocking and feeding element being movable between an operative position, wherein it is close to the feeding conduit and is adapted to block a further product of the row, and an inoperative position, far away from the feeding conduit; said second blocking and feeding element being positioned along the feeding direction at a distance from the first blocking and feeding element that defines said bottom end portion; - a detecting device adapted to detect, at an upper zone of the bottom end portion of the feeding conduit, when the first blocking and feeding element and the second blocking and feeding element are in respective operative positions, whether or not a product is present, and, in case such a product is absent, to send a rejection signal to a rejection device to reject the bottom below, or the capsule formed by the bottom below. - a feeding conduit that defines a feeding direction and is adapted to slidingly housing a row of products, said feeding conduit including a bottom end portion adapted to slidingly house, below the row of products, a group including one or more products aligned; - a blocking and feeding system for blocking the row of products and feeding each bottom below with one group of products; said blocking and feeding system including a first blocking and feeding element and a second blocking and feeding element; said first blocking and feeding element being movable between an operative position, wherein it closes the feeding conduit and is adapted to support and block a first product of the group, and an inoperative position, wherein the feeding conduit at the bottom end portion is inferiorly open; said second blocking and feeding element being movable between an operative position, wherein it is close to the feeding conduit and is adapted to block a further product of the row, and an inoperative position, far away from the feeding conduit; said second blocking and feeding element being positioned along the feeding direction at a distance from the first blocking and feeding element that defines said bottom end portion; - a detecting device adapted to detect, at an upper zone of the bottom end portion of the feeding conduit, when the first blocking and feeding element and the second blocking and feeding element are in respective operative positions, whether or not a product is present, and, in case such a product is absent, to send a rejection signal to a rejection device to reject the bottom below, or the capsule formed by the bottom below.