PURPOSE: To remove adhered algaes simply and certainly, by providing an ultrasonic vibrator to a running truck provided on a girder running along a rectangular settling basin in a suspended state.

CONSTITUTION: A flooding weir 4 is provided in the running direction of a girder 3 along the wall surface of a settling basin or to the central part thereof and a running truck 5 is provided on the girder 3 in a freely runnable manner. An ultrasonic vibrator is provided to the running truck 5 so as to be suspended in the flooding weir 4. To the lower part of the running truck 5, a support lever 7 is provided in a protruded state and a vibrator 8 is fixed to the lower part of the support lever 7 which is in turn supported by the running truck 5 through a bearing 9 in a freely revolvable manner. A gear 10 is provided to the upper end of the support lever 7 in a protruded state and engaged with the gear 11 of a shaft revolved by a handle and a drive apparatus to revolve the support lever 7 and the vibrator 8 is revolved so as to be moved to the side of a flooding plate or the side of the tank wall surface opposed to said flooding plate.