We have made observations of the dark cloud, B5 in the transitions of H2CO, J = 1 10 ― 1 11, and 2 12 ― 1 11. We compared the H2CO result with the observational results of CO and with the visual extinction. There exists an overall correspondence of molecules and extinction. However, a detailed agreement is lacking. We discussed the kinematics and the spatial relationship of molecules and extinction in this cloud.