A gel composition which retains a high viscosity in a wide polarity range of from low polarity to high polarity and has excellent long-term viscosity stability. It is characterized by containing cation-modified clay minerals in which the cations are quaternary ammonium cations (I) and quaternary ammonium cations (II). The cation-modified clay minerals preferably comprise a clay mineral (A) modified with the cations (I) and a clay mineral (B) modified with the cations (II) in an (A)/(B) weight ratio of from 55/45 to 99.9/0.1. (I) (R<1> represents C1-9 alkyl, phenyl, or C7-9 aralkyl; and R<2> represents C10-36 alkyl.) (II) (R<3> and R<4> each independently represents C10-36 alkyl.)
