A recording medium containing cassette removably mounted in a body of an image forming apparatus, comprising: a recording medium support plate configured to allow a stack of recording media to be placed thereon; a biasing member configured to bias upward the recording medium support plate; and a width cursor (37a, 37b) configured to position the stack of recording media in a widthwise direction (A, #A) perpendicular to a conveyance direction of the recording medium, wherein the recording medium support plate is allowed to swing so that a downstream portion in the conveyance direction of the recording medium support plate is movable upward and downward, the width cursor includes a first limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and an amount of the stack of recording media is larger than a predetermined value, and a second limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and the amount of the stack of recording media is smaller than the predetermined value, the first limiting portion is in contact with a topmost recording medium of the stack of recording media when the amount of the stack of recording media is larger than the predetermined value, the second limiting portion is in contact with the recording medium support plate moved upward by the biasing member when limiting the upward movement of the recording medium support plate, and the first limiting portion is provided at an uppermost portion of the width cursor and characterised by protruding inward of the recording medium containing cassette in the width direction (A, #A) from the width cursor. a recording medium support plate configured to allow a stack of recording media to be placed thereon; a biasing member configured to bias upward the recording medium support plate; and a width cursor (37a, 37b) configured to position the stack of recording media in a widthwise direction (A, #A) perpendicular to a conveyance direction of the recording medium, the recording medium support plate is allowed to swing so that a downstream portion in the conveyance direction of the recording medium support plate is movable upward and downward, the width cursor includes a first limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and an amount of the stack of recording media is larger than a predetermined value, and a second limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and the amount of the stack of recording media is smaller than the predetermined value, a first limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and an amount of the stack of recording media is larger than a predetermined value, and a second limiting portion configured to limit the upward movement of the recording medium support plate when the recording medium containing cassette is outside the body of the image forming apparatus and the amount of the stack of recording media is smaller than the predetermined value, the first limiting portion is in contact with a topmost recording medium of the stack of recording media when the amount of the stack of recording media is larger than the predetermined value, the second limiting portion is in contact with the recording medium support plate moved upward by the biasing member when limiting the upward movement of the recording medium support plate, and the first limiting portion is provided at an uppermost portion of the width cursor and characterised by protruding inward of the recording medium containing cassette in the width direction (A, #A) from the width cursor.