This paper proposes to evaluate the elastic components of force sensors based on three criteria, that is, the strain gage sensitivity, the force sensitivity, and the minimum rigidity. The strain gage sensitivity is defined as the Euclidean norm of a row vector of the sensor compliance matrix. The force sensitivity is the minimum singular value of the sensor compliance matrix. The minimum rigidity means the inverse of the maximum singular value of the compliance matrix at the point to which forces and moments are applied. When the number of strain gages is larger than six, there is variety in inverting strain gage signals into the force information. By using this fact, it is also proposed to design the elastic component so that a Wheatstone Bridge should work as the decoupling circuit of the force information. A six axes force sensor is designed as an example to show the effectiveness of the proposed criteria and signal processing method.