Classifying rocks based on their degree of fissure is essential for various geological, engineering, and environmental applications. Therefore, determining fissures’ severity can provide valuable insights into rock stability, groundwater flow patterns, and potential risks associated with construction projects. This paper presents a comprehensive investigation of the classification of rocks based on their degree of fissures using the values of ultrasonic pulse velocity and porosity. Also, the study involves the acquisition of ultrasonic velocity data from non-destructive testing tests and the porosity from laboratory tests on sedimentary rocks, namely, sandstones, shales, and coals from two different locations, i.e., the North Karanpura Coalfield, Ranchi in Jharkhand, and Raniganj Coalfield, in West Bengal in India. Then the values of the degrees of fissures are calculated using the empirical equation given by Fourmaintraux (Characterization of rocks laboratory tests. Paris, 1976 [6]), and then the rocks are classified accordingly. Results from the study show that sandstone and shale lie in the zone of strong to moderate fissured rocks, while coal lies between moderately fissured and slightly fissured rocks.