PURPOSE: To accurately set the time constant of a time constant circuit based on a setting voltage VS by detecting an RC error caused by dispersion in the IC manufacture process and using the detected error so as to automatically adjust the dispersion in the time constant caused by the RC error.

CONSTITUTION: A dispersion detection circuit 20 detects an RC error and gives a control voltage Vc depending on the detected result to a transistor(TR) 102 of a control section 10 of a time constant circuit to control a current source 106 being a drive source and a current source 108 of a TR 104 receiving a setting voltage Vs. Thus, the control section 10 outputs a control voltage independently of the RC error in which a transconductance gm of the time constant circuit is expressed in gm=gm0(1+AoVs).