Provided is an orthotic device that achieves both a holding force and an orthotic force necessary for improvement of deformation and function of a lower limb and trackability to friction, fluctuation, compression and the like occurring during operation between an orthotic site and the orthotic device, is easy to wear, does not impair appearance during wearing, and in addition, maintains an appropriate holding force and orthotic force for a long period of time, and can be continuously used. A lower-limb orthotic device of the present invention includes: a fabric band A1 covering at least a part of an ankle portion including a malleolus and/or at least a part of a knee portion; a fabric band A2 covering a foot portion including a metatarsal bone; and at least one fabric band B, in which at least a part of the fabric band B covers the foot portion including a fifth metatarsal bone or a cuboid bone, the fabric band B is disposed to be positioned from the foot portion including the fifth metatarsal bone or the cuboid bone to the ankle portion and/or the knee portion, one end of the fabric band B in a longitudinal direction is connected to the fabric band A1, the other end of the fabric band B is connected to the fabric band A2, an interior angle between the fabric band A1 and the fabric band B when the lower-limb orthotic device is worn is 30° to 90°, and at least one of the fabric bands has an extension ratio at a load of 100 N/5 cm of 0.5% or more and 50% or less in a width direction and a longitudinal direction or in either one of the width direction and the longitudinal direction.