A length-adjustable shoe is disclosed. The shoe includes an outsole, an insole attached on the outsole, an upper attached on the insole, means for adjusting a length of the insole, which is provided at the insole, an upper tension member provided at the upper, a lower tension member provided at the outsole, and means for fastening a front part and a rear part of the upper divided by the upper tension member to maintain a size of the shoe at a wearer's foot size. The shoe is extended and contracted longitudinally without change of an outer shape of the shoe, by the length-adjusting means, the upper tension member, the lower tension member, and the fastening means. The shoe can accommodate a wearer suffering hallux valgus or hallux varus, a wearer with both feet having different sizes, and a wearer with rapid growth rate. The shoe can be worn by a wearer for a long period of time without needless expenditure due to purchase of two pair of shoes.