PURPOSE: To improve the durability of seals by arranging multiple seals between a case and a pump shaft at a gap, and forming the opening section of a drain passage communicated to the outside of the case in this gap.

CONSTITUTION: A seal 13 is located on the inside of a seal 12, and its inner periphery 13a is liquid-tightly provided on a pump shaft 7 via a pair of O-rings 17. A cooling water seal section 13c and an oil seal section 13d are formed on the inner periphery 13a, the outer periphery 13b is liquid-tightly provided on the clip 16 of the seal 12 via a clip 18, thereby the outer periphery 12a is liquid-tightly provided on a recess 3b indirectly. An opening section 19 is formed on the outer periphery 12a and clip 16 of the seal 12, it is communicated to a drain passage 20 formed on a case 3, and a gap 14 between the seal 12 and seal 13 is communicated to the outside of the case 3.