To provide a method for producing a 1-organoxytetrasiloxane selectively in high productivity.

The method for producing the 1-organoxytetrasiloxane of the general formula:R3R22Si(OR12Si)3OR4 comprises the following process: A cyclotrisiloxane(A) of the general formula:(R12SiO)3 is subjected to ring-opening reaction with a halosilane(C) of the general formula:R3R22SiX in the presence of a quaternary ammonium salt(B) to prepare a 1-halotetrasiloxane(D) of the general formula: R3R22Si(OR12Si)3X, and the component(D) and an organic compound(E) of the general formula:MOR4 are subjected to condensation reaction with each other. In the general formulas, R1 and R2 are each a monovalent hydrocarbon group; R3 is H or a monovalent organic group; R4 is a monovalent organic group; X is a halogen atom; and M is an alkali metal atom or H.