Large groundwater flow into a tunnel during construction may cause crucial problems with safety, schedule, and costs of the construction. It is therefore important to locate the flow paths (e.g. in fractured zones) and to measure the flowrate and hydraulic pressure ahead of the tunnel face in advance for tunnel excavations. The authors have developed a new system for investigating the flow paths in forward drilling called “T-DrillPacker”. This system is very useful to measure the flowrate and pressure of the flow paths while reducing operation risks such as borehole collapses. An inflation packer can be easily installed in forward drilling without pulling out the drilling tubes, instead by sending the packer inside the tubes. However, the installation of the packer is generally time consuming because many rods must be added sequentially and manually to send the packer to the borehole bottom (rod-feed type). Therefore, to further speed up the measurement operations, we have developed a new “pressure-feed type” system in which the packer is pumped into the borehole bottom by high water pressure very quickly. In this paper, we describe the overview of the new measurement system with preliminary results obtained from a validation test.