A litter device for a pet, comprising: a base configured to be placed on a support surface, the base comprising a recessed portion that comprises a recess surface defining an opening; a drum rotatably connected to the base and partly received in the recessed portion, the drum comprising an outer lateral surface, the recess surface and a portion of the outer lateral surface that faces the recess surface defining a gap (d) therebetween and forming a passage in communication with the opening, and the recess surface configured to guide litter particles entering the passage to pass through the opening to fall on the support surface; and weight measuring mechanism, wherein the weight measuring mechanism is arranged in the base and is configured to measure a weight of the drum, wherein the weight measuring mechanism comprises a support member, a weight sensor, and a leg, the support member is arranged in the base, the weight sensor is connected to and arranged under the support member, the weight sensor is connected to and arranged above the leg, and the leg passes through the base to be in contact with the support surface, and wherein the base comprises an upper housing and a lower housing that are connected to each other, the upper housing defines the recessed portion, the opening passes through the upper housing and the lower housing, the lower housing defines a chamber and a through hole in communication with the chamber, the support member, the weight sensor, and the leg are arranged in the chamber, the support member is securely connected to the upper housing, and the leg passes through the through hole. a base configured to be placed on a support surface, the base comprising a recessed portion that comprises a recess surface defining an opening; a drum rotatably connected to the base and partly received in the recessed portion, the drum comprising an outer lateral surface, the recess surface and a portion of the outer lateral surface that faces the recess surface defining a gap (d) therebetween and forming a passage in communication with the opening, and the recess surface configured to guide litter particles entering the passage to pass through the opening to fall on the support surface; and weight measuring mechanism, wherein the weight measuring mechanism is arranged in the base and is configured to measure a weight of the drum, wherein the weight measuring mechanism comprises a support member, a weight sensor, and a leg, the support member is arranged in the base, the weight sensor is connected to and arranged under the support member, the weight sensor is connected to and arranged above the leg, and the leg passes through the base to be in contact with the support surface, and wherein the base comprises an upper housing and a lower housing that are connected to each other, the upper housing defines the recessed portion, the opening passes through the upper housing and the lower housing, the lower housing defines a chamber and a through hole in communication with the chamber, the support member, the weight sensor, and the leg are arranged in the chamber, the support member is securely connected to the upper housing, and the leg passes through the through hole.