PROBLEM TO BE SOLVED: To provide a seat surface sensor unit capable of operating a brake mechanism as desired even when a difference occurs in the amount of seat surface sinking, and a wheel chair having the seat surface sensor unit.SOLUTION: A seat surface sensor unit comprises: a fixing member 50 which is fixed to a body frame for supporting a seat, and in which a first guide groove 56 and a second guide groove 58 bent with respect to the first guide groove are formed； a rotary member 30 having a seat surface sensor part 18 at one end part, which sinks downward when a user is seated on the seat, and pivotally supported on the fixing member in a rotatable manner； a piece member 60 mounted in a manner capable of reciprocating between the first guide groove and the second guide groove of the fixing member； and a force transmission wire 15 whose one end is fitted to the piece member and the other end 17 is connected to a brake part for exerting a brake force to a wheel. The piece member is forcibly moved from the first guide groove to the second guide groove side so that a reaction force is not transmitted from the brake part to the seat surface sensor part.SELECTED DRAWING: Figure 8
