Disclosed is a corrugated paperboard sheet feeding apparatus which comprises: a plurality of sheet feeding rollers rotatable to feed a bottommost one of a plurality of stacked corrugated paperboard sheets; an up-and-down member movable up and down with respect to the plurality of sheet feeding rollers; a drive motor; a motion conversion mechanism configured to convert a unidirectional rotation of the drive motor into a motion for causing the up-and-down member to be moved up and lowered, and transmit the converted motion to the up-and-down member; and an up-and-down control section configured to perform variable speed control for the unidirectional rotation of the drive motor, according to a given up-and-down speed control pattern, wherein the up-and-down control section is operable to change the up-and-down speed control pattern in conformity to a sheet length of the corrugated paperboard sheet in a feeding direction.