To obtain a new propynyl compound useful as an intermediate for producing 3-Z-(1-propenyl)-2,2-dimethylcyclopropionate industrially advantageously as well.

This new propynyl compound is expressed by formula I (R is a 1-4C alkyl or H), e.g. ethyl trans-3-(1-propynyl)-2,2-dimethylcyclopropionate. The compound of formula I is obtained e.g. by reacting a compound of formula II (R is a 1-4C alkyl) with 3-10 mol base (an amine such as 1,8- diazabicyclo-[5,4,0]-7-undecene, an alkali metal alkoxide such as sodium methoxide, or the like) based on 1 mol of the compound of formula II in a usual solvent (e.g. hydrocarbons such as benzene, ethers such as tetrahydrofuran, alcohols such as methanol, dimethylformamide, or the like) at 20°C to the boiling point of the solvent (or 150°) for 30 min to 96 h.