A leg type mobile robot, in which a downsizing and wait-saving of floor reaction force detector to be installed on the foot is enabled. The center Pb of the force sensor is disposed on the position Pa where the distance to the remotest position of ground area provided on the bottom of each plate spring part S1 to S4 is minimum in the standing-still state of the robot R, and the distance L1, L2, L3, and L4 to the remotest point of the ground area of each plate spring part S1, S2, S3, and S4 is equal. The center Pc of the ankle joint is offset in a rearward direction with respect to the position Pa in a plane view.