Novel amphiphilic siloxane copolymers (P1-P10) were synthesized from an oligo(dimethylsiloxane) monomer, 1, and (trimethylammonio)ethyl acrylate, 2. These compounds could form stable monolayers on the air/water interface in the absence and presence of potassium poly(vinylsulfate) (PVSK) in the subphase. The monolayers prepared in the presence of PVSK were two-dimensionally cross-linked at the interface and showed more densely packed structure than none-cross-linked monolayer; however, the direct observation of the monolayer using a fluorescence microscope revealed that the cross-linking induced disorder in the monolayer structures. On the other hand, when the anionic polymer was injected into the subphase after the monolayer formation at the interface, homogeneous microscope images were obtained. These monolayers with two-dimensional network structures could be transferred onto solid substrates by the conventional; Langmuir-Blodgett (LB) technique.