To actualize an execution value type signal converter at low cost and to implement execution value operation by a simple method by providing a means which squares an input substantially and a means which extracts the square root of the squared output and composing the squaring means and square root extracting means of general electronic components including an operational amplifier.

A squaring circuit 1 squares an input signal of execution value level and outputs the result to a square root extracting circuit 2 of the next stage and the square root extracting circuit 2 converts the squared signal to a DC signal and outputs it to the outside. The concept of this block constitution is a conventional execution value type signal converter, but this invention is characterized by that each block is composed of a general electronic component including an operational amplifier. thus, a circuit is constituted by using general electronic components which are distributed well on the market and has high industrial productivity and then the signal converter which converts and outputs a desired operation solution needed for process control, etc., can be actualized at low cost. Specially, this is suitable for respective process instrumentation fields.