Lugeon test is the most universal for investigating permeability of bedrock. But there are many cases which we can not understand reasonably results of the investigation, in spite of the test which is very simple hydrodynamics systems. We concluded the cause of it that there is the large error in the value of the coefficient of pressure loss of water supplying systems. Therefore we have developed the Lugeon tets equipment which is needless to take into consideration of pressure loss of the test systems for calculating permeability from the results. The main points of this development were to measure directly and accurately pressure of the test section in bore hole. For the purpose of measuring it, we have produced the packer combined a pressure transducer and an air packer. Using it, we have repeated many test at the laboratory and the actual bore holes. As a result, it was shown that this equipment is very useful for Lugeon test. Moreover it became clear to be able to use as a equipment of JFT and permeability test at low pressure, low difference water head.