A grease is a semi-fluid dispersion of a thickener in a base oil. Thickener fibers form a network disperses as fiber in grease forming a network structure, and the base oil is likely kept in the thickener network by capillary force. Grease structure has been commonly modeled based on thickener fibers observed by TEM. The thickener fibers and the bulk grease can cover a wide range of size from nm to µm and µm to mm, respectively. Therefore, a detailed understanding of grease structure may necessitate complex observation techniques including visual inspection, optical microscopy (OM) and electron microscopy (TEM or SEM). Although thickener fibers can hardly be observed by OM, the use of confocal laser fluorescence microscopy (CLFM) in this work enabled a close observation of the fibers and proved a three-dimensional grease structure. The author’s CLFM, and TEM SEM, observations revealed a hierarchical structure of grease, which is formed as follows from low to high levels: fibrils assemble to compose fibers, and a mix of fibrils and fibers composes the network. Incorporating the results into the conventional model, hierarchical 2D and 3D models of grease structure were suggested.