Patent ID: 8550452

Claim:
A sheet feeder comprising: a sheet accommodating portion which accommodates sheets; a lift plate which is supported on a bottom face of the sheet accommodating portion such that an end part of the lift plate on an upstream side with respect to a sheet feed direction acts as a rotation pivot and on a top face of which the sheets are placed; an actuating plate which raises and lowers the lift plate by moving between a first position where the actuating plate lies flat along the bottom face of the sheet accommodating portion while in contact with, from below, an end part of the lift plate on a downstream side with respect to the sheet feed direction and a second position where the actuating plate is raised a predetermined angle from the bottom face of the sheet accommodating portion; an actuating plate driving member to which the actuating plate is fixed and of which one end is coupled to a raising/lowering member provided in an image forming apparatus body; and an engagement portion which is provided on a reverse face of the lift plate and which engages with a rotating-side edge of the actuating plate when the actuating plate is in the first position and disengages from the rotating-side edge of the actuating plate as the actuating plate rotates from the first position to the second position, wherein a muffling member is attached to at least one of contact surfaces between the engagement portion and the rotating-side edge of the actuating plate.