The structure of an oriented slit- shaped micropore system in the boehmite glassy film which consists of ordered aggregates of boehmite platelets was studied by molecular resolution analysis using high-resolution N2 and organic vapor (CH2Cl2, benzene, and n-nonane) adsorption. The DR plots for the adsorption isotherms of N2 were divided into three linear regions, which indicates the presence of three different sized micropore groups. From the molecular sieve effect of the probe molecules, the X-ray diffraction data of boehmite film, and the t-plot analysis of N2 adsorption isotherm, the widths of the three different sized micropores were estimated as 0.3, approximately 0.7, and approximately 1.3 nm.