A lower leg supporter is provided which can support a gastrocnemius muscle from upper, lower, left, and right sides without interfering with movement of an Achilles tendon and which can suppress excessive vibration or deformation of the gastrocnemius muscle to reduce a wearers fatigue. The lower leg supporter includes a first anchor section 2 that secures a tubular knitted fabric to a below-knee part, a second anchor section 3 that secures the tubular knitted fabric to an above-ankle part, and a gastrocnemius muscle support section 4 that is knitted in a substantially X-shape intersected around a portion corresponding to a joining part 102a of a gastrocnemius muscle 101 and an Achilles tendon 102 on the back surface side of the tubular knitted fabric, that joins two ends of the substantially X-shaped knitted fabric to the first anchor section 2 to support the gastrocnemius muscle 101, that joins the other two ends of the substantially X-shaped knitted fabric to the second anchor section 3, and that extends to both edges of the Achilles tendon.