A resistance sensing mechanism including a resistance adjusting unit including a holder frame, a locating sleeve disposed above the holder frame, an adjustment screw rod rotatably inserted through the locating sleeve and a screw nut threaded onto the adjustment screw rod and pivotally connected to the holder frame, and a sensor unit including a first linkage pivotally connected with one end to the screw nut, a second linkage having one end pivotally connected to an opposite end of the first linkage and an opposite end pivotally connected to the locating sleeve, a sensor mounted at one of the first and second linkages and a sensible member mounted at the other of the first and second linkages to face toward the sensor. Subject to the linkage relationship between the first and second linkages, the distance between the sensor and the sensible member can be changed, thereby generating a relative sensing signal.