Patent ID: 8777213

Claim:
A recording medium storage cassette, detachably mountable to an image forming apparatus main body comprising: a housing, which is constituted by a cassette base and a plurality of wall portions provided upright at peripheral end portions of the cassette base, for storing a recording medium of a sheet form; and a recording medium stacking plate, which is pivotably provided to the housing and has one end raised and lowered in accordance with a stacking amount of the recording medium, for pressing the recording medium against a pickup roller which is provided on the image forming apparatus main body side; a first notch portion, which is formed in, among the plurality of wall portions, a wall portion provided upright in a feeding direction of the recording medium, the first notch portion being opened toward an upper end of the wall portion and formed at a position facing a feeding roller pair, which is provided on the image forming apparatus main body side, for separating and feeding the recording medium inside the housing fed from the pickup roller; second notch portions formed at both end portions in a longitudinal direction of an upper end portion of the wall portion; and recording medium regulating portions formed between the first notch portion and the respective second notch portions, the recording medium regulating portions regulating movement in the feeding direction of the recording medium inside the housing, wherein the recording medium regulating portions each have a mountain shape with a peak when viewed from the feeding direction of the recording medium, the peaks being arranged closely inside width-direction ends of a minimum-width interval that corresponds to the width of a minimum-width recording medium for which the housing is configured to store in a predetermined position, an interval of peaks of the recording medium regulating portions is larger than a width of the feeding roller pair, a height of the peaks of the recording medium regulating portions is equal to or larger than a stacking height of a maximum amount of recording medium storable inside the housing but smaller than a height at which the recording medium stacking plate makes contact with the pickup roller, and the first notch portion has a taper portion which widens toward the peaks.