Micro-CT is a nondestructive scanning device that is capable of capturing three dimensional structures at _m level. With the spread of this device uses in medical fields, it is expected that this device may bring further understanding of the human anatomy by analyzing three-dimensional micro structure from volume of in vivo specimens captured by micro-CT. In the topic of micro structure analysis of lung, the methods for extracting surface structures including the interlobular septa and the visceral pleura were not commonly studied. In this paper, we introduce a method to extract sheet structure such as the interlobular septa and the visceral pleura from micro-CT volumes. The proposed method consists of two steps: Hessian analysis based method for sheet structure extraction and Radial Structure Tensor combined with roundness evaluation for hollow-tube structure extraction. We adopted the proposed method on complex phantom data and a medical lung micro-CT volume. We confirmed the extraction of the interlobular septa from medical volume from experiments.