We observed the osteological development in larvae and juveniles of Korean spotted sleeper Odontobutis interrupta bred in the laboratory in April 2014. Immediately after hatching, the prelarvae, which were about 4.27 mm long, showed ossification of the premaxillary bones in the upper jaw and the dentary and articular bones in the lower jaw. At 7.11 mm, the larvae showed complete fusion of the post-cleithra and ossification of the scapulae with the appearance of one hole. At 8.65 mm, the larvae showed ossification of seven ribs from the third abdominal vertebra and an increase in the length of the neural spine and hemal spine. The number of caudal fin rays increased to 19. At 11.9 mm, the juveniles showed ossification of three procurrent rays on the side of the parhypural bone as well as ossification of two procurrent rays on the side of the epural bone, indicating the complete ossification of all spicules.