A connector 10 includes a terminal 5 having an electric connecting portion 52 connected with a mating member 9 at one end of the terminal 5 so as to be placed on the mating member 9 and fastened by a bolt 11 and a nut 12 and a wire connecting portion 55 joined with a terminal end of the electric wire 6 at the other end of the terminal 5, and a connector housing 4 having a terminal receiving section 41, and a water seal plug 1 arranged around the electric wire 6 to seal watertightly the terminal receiving section 41. The water seal plug 1 includes integrally a rubber water seal member 3 and a resin member 2 made of synthetic resin. The water seal member 3 includes a cylindrical main body 30 and an outer lip 31 abutting on an inner surface of the terminal receiving section 41, and a plurality of inner lips 32a, 32b, 32c abutting on an outer surface of the electric wire 6. A first inner lip 32a at the nearest position to the terminal 5 is formed to have a lower projecting height then that of the second inner lip 32b and the third inner lip 32c.