To obtain a film-forming assistant for an aqueous composition, having low toxicity to organisms, low odor, high safety and low viscosity and exhibiting high compatibility to the aqueous composition, and the aqueous composition containing the assistant.

The film-forming assistant is expressed by formula (1) [R1, R2 and R3 are each independently H, a specific alkyl, a cycloalkyl or an aryl; (p), (r) and (s) are each an integer of 0-9; (q) is an integer of 1-9; and 1≤p+q+r+s≤9 and {r<s or (r=s and p≤q)}]. The aqueous composition contains 0.1-30 pts.mass of one or more kinds of the assistants per 100 pts.mass of the solid component of the water-soluble and/or water-dispersible composition.