To monitor the viscosity of paste at any time and to suppress the paste applied amt. of a roll to a necessary min. amount.

In a viscous liquid coating apparatus for applying the paste, which is supplied to a storage tray 4 through a flow channel 21, to a rotary paste roll 5 and scooping up this paste to transfer the same to an article to be coated, a bypass circuit 24 is provided to the flow channel 21 and a viscosity measuring device V for measuring viscosity, on the basis of the rotary load of a rotor is provided to the bypass circuit 24. Since the measured value of the viscosity measuring device V is almost accurately correlated with the amt. of the paste adhering to the paste roll 5, the viscosity of the paste is adjusted on the basis of the measured value and a necessary min. amt. of the paste is scooped up by the paste roll 5.