PURPOSE: To provide a controlling method of a papermaking machine producing a paper sheet having a uniform basis weight profile.

CONSTITUTION: Paper profile is detected by relevant detector 8 to scan the width direction of paper and then transduced by a transducer 9 into the corresponding electrical data as the basis weight profile data in the width direction, which is, in turn, operated by a relevant operational device 10 to output the amount of slice lip to be adjusted to a driving control section 16; in this case, the terminal end on the side of operating the paper width direction is set at 0 in terms of x-coordinate, followed by conducting a regression analysis by the method of least squares using a quadratic expression of the formula (1): Y=ax2+bx+c [(a), (b) and (c) are each a real number; Y is basis weight (g/m2); (x) is a coordinate in the paper width direction]. From the resultant coefficient (a), the amount S of the slice lip to be adjusted is calculated by using the formula (2): S=ak+L [(a), (k) and L are each a real number; S is the amount of the slice lip to be adjusted (mm)], and based on the S value, the divergence of the slice lip is controlled in response to the respective instructions from a temperature controller 11 and a pressure controller 12.