A loom having a weft tensioning device comprising: a weft-gripping mechanism part that is arranged at the downstream side in a picking direction of a weft relative to a picking passage of a reed and that is fixed on a sley, the weft-gripping mechanism part comprising: an insertion passage that is formed with a periphery being enclosed by a wall surface and into which a tip portion of the picked weft is inserted, and a pressing member that is capable of gripping the tip portion of the weft against an inner surface of the insertion passage, characterized in that the weft-gripping mechanism part further comprises: an air cylinder mechanism that actuates the pressing member and causes the pressing member to grip the tip portion of the weft; and a tensioning member that is fixed to a frame of the loom, is able to come into contact with the weft between the reed and the weft-gripping mechanism part when the reed is swinging in a beating direction in the state in which the tip portion of the weft is gripped by the weft-gripping mechanism part, and applies tension to the weft by relative displacement with respect to the reed; wherein the insertion passage is specified such that an opening area of an entry portion thereof is equal to or greater than a passage cross-sectional area of the picking passage of the reed, and the insertion passage is formed such that a passage cross-sectional area thereof progressively decreases from the entry portion side toward the side of a region at which the tip portion of the weft is gripped. a weft-gripping mechanism part that is arranged at the downstream side in a picking direction of a weft relative to a picking passage of a reed and that is fixed on a sley, the weft-gripping mechanism part comprising: an insertion passage that is formed with a periphery being enclosed by a wall surface and into which a tip portion of the picked weft is inserted, and a pressing member that is capable of gripping the tip portion of the weft against an inner surface of the insertion passage, characterized in that an insertion passage that is formed with a periphery being enclosed by a wall surface and into which a tip portion of the picked weft is inserted, and a pressing member that is capable of gripping the tip portion of the weft against an inner surface of the insertion passage, the weft-gripping mechanism part further comprises: an air cylinder mechanism that actuates the pressing member and causes the pressing member to grip the tip portion of the weft; and a tensioning member that is fixed to a frame of the loom, is able to come into contact with the weft between the reed and the weft-gripping mechanism part when the reed is swinging in a beating direction in the state in which the tip portion of the weft is gripped by the weft-gripping mechanism part, and applies tension to the weft by relative displacement with respect to the reed; wherein the insertion passage is specified such that an opening area of an entry portion thereof is equal to or greater than a passage cross-sectional area of the picking passage of the reed, and the insertion passage is formed such that a passage cross-sectional area thereof progressively decreases from the entry portion side toward the side of a region at which the tip portion of the weft is gripped. an air cylinder mechanism that actuates the pressing member and causes the pressing member to grip the tip portion of the weft; and a tensioning member that is fixed to a frame of the loom, is able to come into contact with the weft between the reed and the weft-gripping mechanism part when the reed is swinging in a beating direction in the state in which the tip portion of the weft is gripped by the weft-gripping mechanism part, and applies tension to the weft by relative displacement with respect to the reed; wherein the insertion passage is specified such that an opening area of an entry portion thereof is equal to or greater than a passage cross-sectional area of the picking passage of the reed, and the insertion passage is formed such that a passage cross-sectional area thereof progressively decreases from the entry portion side toward the side of a region at which the tip portion of the weft is gripped.