Abstract: Disclosed herein is an apparatus for preventing pollution of a groundwater borehole, which increase water-tightness. The apparatus for preventing pollution of a groundwater borehole has a structure that both sides of an underwater motor pump supported by a first intake pipe having a groundwater borehole for discharging groundwater to the outside are all supported inside a second intake pipe connected with the first intake pipe. The apparatus always maintains balance of the motor pump inside the intake pipes, thereby preventing displacement occurring by supporting only a side of the motor pump like the prior arts, and preventing water leakage and providing watertight efficiency by maintaining the close contact efficiency of an induction pipe connector mounted inside the second intake pipe.