A vehicle tilt detecting apparatus includes a load sensor provided for detecting a load acts on a supporting portion, a load detecting portion detecting a partial load value of the load placed on the seat on the basis of an output from the load sensor and outputting a detected load value, first interrelating portion indicates a relation between a detected load value of no-load and a front-rear tilt angle of the vehicle, unoccupied seat determining portion determining an unoccupied state, where no-load is placed on the seat, when the detected load value outputted from the load detecting portion is less than an unoccupied seat determining value and front-rear tilt angle calculating portion calculating the front-rear tilt angle corresponding to the detected load value outputted from the load detecting portion, on the basis of the first interrelating portion, when the unoccupied seat determining portion determines the unoccupied state.