The present invention provides a process for producing 2',3'-didehydro-3'-deoxy-4'-ethynylthymidine, which is useful as a medicine, in an efficient and industrially advantageous manner, and more specifically, provides a process for producing 2',3'-didehydro-3'-deoxy-4'-ethynylthymidine as shown below. (wherein R 1 and R 2 independently represent a protective group for a hydroxy group, or R 1 and R 2 together form a protective group for two hydroxy groups, R 3 and R 4 independently represent a protective group for a hydroxy group, R 5 represents a protective group for a hydroxy group, R 6 represents a protective group for a hydroxy group, X represents a leaving group, and Y represents a halogen atom.)
