A lower leg supporter supports 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 such muscle to reduce a wearer's fatigue. The lower leg supporter includes a first anchor section that secures a tubular knitted fabric to a below-knee part, a second anchor section that secures the tubular knitted fabric to an above-ankle part, and an X-shaped gastrocnemius muscle support section located at a joining part of such muscle and an Achilles tendon on the back surface side of the tubular knitted fabric. Two ends of the X-shaped knitted fabric are joined to the first anchor section to support the gastrocnemius muscle. The other two ends of the X-shaped knitted fabric are joined to the second anchor section, and extend to both edges of the Achilles tendon.