Abstract: A connecting device is comprised of a first housing having therein a pair of parallely spaced first passages each of which has a proximal end and a distal end, a male terminal accommodated in each of the first passages and having a proximal end to which a first wire is connected and a distal end, a second housing having therein a pair of parallely spaced second passages each of which has a proximal end and a distal end fitted into the distal end of the corresponding first passage, a female terminal accommodated in each of the second passages, having a proximal end to which a second wire is connected and a distal end engaged with the distal end of the corresponding male terminal, and an amount of viscous oily substance positioned in the neighbourhood of a portion at which the distal end of the male terminal and the distal end of the female terminal are in engagement with each other in such a manner of an establishment of conductivity therebetween.