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The transient pulse method for measuring the permeability of intact rock was proposed after Brace et al. In this study, the testing apparatus based on Brace's idea is developed, and the effects of both pressure gradient and confining pressure are investigated experimentally for six kinds of rocks. Furthermore, the obtained test results are compared with the theoretical calculations where the effects of porosity and compressibility of rocks are taken into consideration.Main results are summarized as follows: 1) The permeability of the rock, which is less than 10-9cm/sec, is successfully measured with the transient pulse method. 2) If the permeability of the rock is greater than 10-9 cm/sec, it increases as the pressure gradient increases and decreases as the confining pressure increases. Consequently, it is important to choose the testing conditions according to in-situ state of stresses for these rocks.3) The effect of pressure gradient or confining pressure is very small for the rocks which have the permeability of less than 10-9 cm/sec. 4) If the effects of porosity and compressibility of the rock are considered in establishing the theoretical relationship between the permeability and the presure-decay data, larger permeability is obtained than that estimated after Brace at least for the rock which contains only spherical pores.

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