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 R1 and R2 independently represent a protective group for a hydroxy group, or R1 and R2 together form a protective group for two hydroxy groups, R3 and R4 independently represent a protective group for a hydroxy group, R5 represents a protective group for a hydroxy group, R6 represents a protective group for a hydroxy group, X represents a leaving group, and Y represents a halogen atom.)
