A paper container with a stopper, comprising: a container main body including: a body having a square tubular shape and including a front panel, a right side panel, a back panel, and a left side panel; a bottom configured to seal a lower opening of the body; and a flat top configured to seal an upper opening of the body; and the stopper provided on the top, wherein the stopper is provided at a position adjacent to a first top corner portion among four top corner portions of the top, the first top corner portion being formed by a top side of the front panel and a top side (3a, 5a) of any one of the left side panel and the right side panel, and wherein the body includes a first recessed portion in a first body corner portion among four body corner portions formed by the front panel, the right side panel, the back panel, and the left side panel, the first body corner portion being formed between the front panel and any one of the left side panel and the right side panel forming the first top corner portion at which the stopper is provided, the first recessed portion being surrounded by two recessed-portion forming folding line portions (14, 15) extending from a starting point, which is located at the first top corner portion or at a position slightly away from the first top corner portion, branching from the starting point to the front panel and any one of the left side panel and the right side panel so as to extend toward the bottom direction, and joining together at an end point, which is located at a position within which the two recessed-portion forming folding line portions (14, 15) extend until after reaching a first bottom corner portion formed by a bottom side of the front panel and a bottom side of any one of the left side panel and the right side panel, such that when the first body corner portion is seen from an inner surface side of the container, the first recessed portion causes a gentle swelling to form in the first body corner portion, and an edge portion of the first recessed portion on the first top corner portion forms an inner inclined surface inclined toward the stopper, the first body corner portion being arranged in a trough-like manner so as to be capable to guide a matter in the container main body toward the stopper, such that the matter may be smoothly discharged. a container main body including: a body having a square tubular shape and including a front panel, a right side panel, a back panel, and a left side panel; a bottom configured to seal a lower opening of the body; and a flat top configured to seal an upper opening of the body; and a body having a square tubular shape and including a front panel, a right side panel, a back panel, and a left side panel; a bottom configured to seal a lower opening of the body; and a flat top configured to seal an upper opening of the body; and the stopper provided on the top, wherein the stopper is provided at a position adjacent to a first top corner portion among four top corner portions of the top, the first top corner portion being formed by a top side of the front panel and a top side (3a, 5a) of any one of the left side panel and the right side panel, and wherein the body includes a first recessed portion in a first body corner portion among four body corner portions formed by the front panel, the right side panel, the back panel, and the left side panel, the first body corner portion being formed between the front panel and any one of the left side panel and the right side panel forming the first top corner portion at which the stopper is provided, the first recessed portion being surrounded by two recessed-portion forming folding line portions (14, 15) extending from a starting point, which is located at the first top corner portion or at a position slightly away from the first top corner portion, branching from the starting point to the front panel and any one of the left side panel and the right side panel so as to extend toward the bottom direction, and joining together at an end point, which is located at a position within which the two recessed-portion forming folding line portions (14, 15) extend until after reaching a first bottom corner portion formed by a bottom side of the front panel and a bottom side of any one of the left side panel and the right side panel, such that when the first body corner portion is seen from an inner surface side of the container, the first recessed portion causes a gentle swelling to form in the first body corner portion, and an edge portion of the first recessed portion on the first top corner portion forms an inner inclined surface inclined toward the stopper, the first body corner portion being arranged in a trough-like manner so as to be capable to guide a matter in the container main body toward the stopper, such that the matter may be smoothly discharged.