Preparation and properties of novel oligo-acene Langmuir-Blodgett films without alkyl chain were investigated. Oligo-acene skeleton is used for the hydrophobic part, instead of conventional long alkyl chains, and substituted with weak hydrophilic groups at the 2- or 3-position. In addition to an amphiphilic balance between the hydrophilic and hydrophobic parts of the molecule, it was revealed that the number of aromatic rings and van der Waals cohesive forces in oligo-acene are crucial for stable monolayer formation. Tetracene-2,3-dialdehyde forms stable condensed monolayer on pure water subphase. This amphiphile gave a Z-type multilayer film on a hydrophilic substrate. The absorption spectra of the multilayer indicated large intermolecular pi-pi interaction between the neighboring amphiphiles,