Provided is a polyorganosiloxane, wherein a value obtained by integrating dw/d log(M) from 2.5≤log(M)≤3.1 is 0 to 10% of a value obtained by integrating dw/d log(M) over the entire range of log (M) in a differential molecular weight distribution curve, wherein the differential molecular weight distribution curve is determined by gel permeation chromatography using the polystyrene calibration curve, has an x-axis showing a logarithmic value log(M) of a molecular weight M and has a y-axis showing dw/d log(M) obtained by differentiating a concentration fraction w with respect to the logarithmic value log(M) of the molecular weight.