Provided is a thickening/stabilizing agent that thickens, gelatinizes, and/or stabilizes a fluid organic substance to a desired viscosity. The thickening/stabilizing agent according to the present invention contains a compound (1) represented by Formula (i) and a compound (2) represented by Formula (ii), in a mole ratio of the compound (1) to the compound (2) of 95:5 to 25:75. The four R1s in Formula (i) represent, identically in each occurrence, a C12-C18 aliphatic hydrocarbon group； and the four R2s in Formula (ii) represent, identically in each occurrence, an C4-C10 aliphatic hydrocarbon group. Formulae (i) and (ii) are expressed as follows:
