The resonant frequency ωx(n) of horizontal shaking of a suspended load W suspended from the distal end of a telescopic boom 9 via wire ropes 14·16 is calculated on the basis of the suspension length Lm(n)·Ls(n) of the wire ropes 14·16; the characteristic frequency ωy(n) in the raising and lowering direction of the telescopic boom 9 is calculated; and, in accordance with an operation for raising and lowering the telescopic boom 9, the filtering control signal Cd(n) of an actuator is generated in which a frequency component in a discretionary frequency range is attenuated at a discretionary ratio with reference to the resonant frequency ωx(n) of the suspended load W, and in which a frequency component in a discretionary frequency range is attenuated at a discretionary ratio with reference to the characteristic frequency ωy(n) in the raising and lowering direction of the telescopic boom 9.