A process for preparing a 5-alken-1-yne compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -C≡CH in which Y in formula represents a hydrogen atom or a hydroxyl group, and when Y represents a hydroxyl group, this may be protected with a protecting group if necessary, Z represents a divalent hydrocarbon group having from 1 to 15 carbon atoms, and R 1 and R 2 represent, each independently, a hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms or bond together to form a divalent hydrocarbon group having from 1 to 6 carbon atoms, R 1 -R 2, the process comprising at least steps of: subjecting (i) an alkenylmagnesium halide compound prepared from a haloalkene compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -X 1 in which Y, Z, R 1 and R 2 are as defined above and X 1 represents a halogen atom, and (ii) an alkyne compound of the following formula: X 2 -C≡C-Si(R 3)(R 4)(R 5) in which X 2 represents a halogen atom, R 3 represents a hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms, and R 4 and R 5 represent, each independently, a monovalent hydrocarbon group having from 1 to 6 carbon atoms or bond together to represent a divalent hydrocarbon group having from 2 to 6 carbon atoms, R 4 -R 5, to a coupling reaction to form a silane compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -C≡C-Si(R 3)(R 4)(R 5) in which Y, Z, R 1, R 2, R 3, R 4, and R 5 are as defined above; and subjecting the silane compound to a desilylation reaction to form the 5-alken-1-yne compound. in which Y in formula represents a hydrogen atom or a hydroxyl group, and when Y represents a hydroxyl group, this may be protected with a protecting group if necessary, Z represents a divalent hydrocarbon group having from 1 to 15 carbon atoms, and R 1 and R 2 represent, each independently, a hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms or bond together to form a divalent hydrocarbon group having from 1 to 6 carbon atoms, R 1 -R 2, the process comprising at least steps of: subjecting (i) an alkenylmagnesium halide compound prepared from a haloalkene compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -X 1 in which Y, Z, R 1 and R 2 are as defined above and X 1 represents a halogen atom, and (ii) an alkyne compound of the following formula: X 2 -C≡C-Si(R 3)(R 4)(R 5) in which X 2 represents a halogen atom, R 3 represents a hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms, and R 4 and R 5 represent, each independently, a monovalent hydrocarbon group having from 1 to 6 carbon atoms or bond together to represent a divalent hydrocarbon group having from 2 to 6 carbon atoms, R 4 -R 5, to a coupling reaction to form a silane compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -C≡C-Si(R 3)(R 4)(R 5) in which Y, Z, R 1, R 2, R 3, R 4, and R 5 are as defined above; and subjecting the silane compound to a desilylation reaction to form the 5-alken-1-yne compound. subjecting (i) an alkenylmagnesium halide compound prepared from a haloalkene compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -X 1 in which Y, Z, R 1 and R 2 are as defined above and X 1 represents a halogen atom, and (ii) an alkyne compound of the following formula: X 2 -C≡C-Si(R 3)(R 4)(R 5) in which X 2 represents a halogen atom, R 3 represents a hydrogen atom or a monovalent hydrocarbon group having from 1 to 6 carbon atoms, and R 4 and R 5 represent, each independently, a monovalent hydrocarbon group having from 1 to 6 carbon atoms or bond together to represent a divalent hydrocarbon group having from 2 to 6 carbon atoms, R 4 -R 5, to a coupling reaction to form a silane compound of the following formula: Y-Z-CR 1 =CR 2 -(CH 2) 2 -C≡C-Si(R 3)(R 4)(R 5) in which Y, Z, R 1, R 2, R 3, R 4, and R 5 are as defined above; and subjecting the silane compound to a desilylation reaction to form the 5-alken-1-yne compound.