A resistance connecting device includes a case inside of which a chamber is formed. The chamber includes inside an activating unit, a gas generating unit, a first connecting portion, and a second connecting portion. The first connecting portion and the second connecting portion extend from the inside to the outside of the case in a mutually separated state and are exposed in the chamber. The activating unit is held at a first position that does not cause contact with either of the connecting portions when the gas generating unit has not been activated and moves up to a second position to cause contact with both of the connecting portions as a result of activation of the gas generating unit. The activating unit, at the second position, functions as a resistor having a predetermined electrical resistance, and connects the connecting portions to one another.