Abstract: A control rod (2) for boiling water reactor comprising four absorber blades (6, 7, 8, 9) which form an orthogonal cross with a cruciform centre (10). The width of the absorber blades coincides with the radial direction of the control rod and the length of the absorber blades coincides with the axial direction of the control rod. Each one of the absorber blades comprises an absorber material distributed in the longitudinal direction, whereby a mean value of the quantity of absorber material per unit of length of the control rod is smaller in the upper part of the control rod than in the lower part thereof. Each one of the absorber blades comprises in its upper part (15) an inner part arranged radially inside an outer part, where the outer part is provided with absorber material whereas the inner part lacks absorber material, whereby said inner part in at least some portion constitutes at least one-fourth of the width of the absorber blade.