This paper describes a development of a curvature sensor using a solid polymer electrolyte (SPE) film. The sensor has a basic structure that an SPE film is sandwiched between thin carbon films. Each carbon is coated with Ag paste and they are covered with polymer films. The SPE film has good flexibility, and can be used in air. In previous research, we clarified output response to deformation of the SPE sensor and the relationship between sensor output and sensor curvature. In this paper, in order to obtain the output characteristics of the curvature sensor, the influence of the position of partial deformation on the sensor output and the relationship between the sensor output and the area size of the deformed part in the SPE film were investigated. As a result, it is found that the sensor output is independent of the position where deformation is applied and that the sensor output has a proportional relation with the area size of the deformation part. Moreover these findings suggest that the sensor output is related to the average of the curvature of the measured surface.