An image forming apparatus comprising: a cassette fitting portion which is provided in a main body of the apparatus and which includes a feed portion that feeds a sheet; and a sheet storage cassette which can be fitted to the cassette fitting portion along a sheet feed direction and which includes a sheet storage portion that stores the sheet; wherein the cassette fitting portion includes a lift plate which is arranged below an end portion of the sheet storage cassette fitted to the cassette fitting portion on a downstream side in the sheet feed direction and which lifts the sheet stored in the sheet storage portion, the sheet storage portion includes a cassette base in which the sheet is stacked on an upper surface and a side wall which is provided so as to stand from end portions of the cassette base on the downstream side, the cassette base is provided with an opening portion in a position opposite the lift plate and in a state where the sheet storage cassette is fitted to the cassette fitting portion, the lift plate is arranged selectively either in a lowered position or a raised position, the lowered position being a position in which the lift plate is arranged below the cassette base and in which the sheet storage cassette is removable with respect to the cassette fitting portion, the raised position being a position in which the lift plate is protruded above the cassette base through the opening portion so as to allow the sheet to be fed with the feed portion, characterized in that the cassette base is provided with a support protrusion portion in an edge portion of the opening portion on the downstream side, the support protrusion portion protrudes to an upstream side in the sheet feed direction so as to support a tip end portion of the sheet, and the lift plate is provided with a slit in an edge portion thereof on the downstream side, the slit is arranged in part opposite the support protrusion portion so as to allow the support protrusion portion to pass through. a cassette fitting portion which is provided in a main body of the apparatus and which includes a feed portion that feeds a sheet; and a sheet storage cassette which can be fitted to the cassette fitting portion along a sheet feed direction and which includes a sheet storage portion that stores the sheet; wherein the cassette fitting portion includes a lift plate which is arranged below an end portion of the sheet storage cassette fitted to the cassette fitting portion on a downstream side in the sheet feed direction and which lifts the sheet stored in the sheet storage portion, the sheet storage portion includes a cassette base in which the sheet is stacked on an upper surface and a side wall which is provided so as to stand from end portions of the cassette base on the downstream side, the cassette base is provided with an opening portion in a position opposite the lift plate and in a state where the sheet storage cassette is fitted to the cassette fitting portion, the lift plate is arranged selectively either in a lowered position or a raised position, the lowered position being a position in which the lift plate is arranged below the cassette base and in which the sheet storage cassette is removable with respect to the cassette fitting portion, the raised position being a position in which the lift plate is protruded above the cassette base through the opening portion so as to allow the sheet to be fed with the feed portion, characterized in that the cassette base is provided with a support protrusion portion in an edge portion of the opening portion on the downstream side, the support protrusion portion protrudes to an upstream side in the sheet feed direction so as to support a tip end portion of the sheet, and the lift plate is provided with a slit in an edge portion thereof on the downstream side, the slit is arranged in part opposite the support protrusion portion so as to allow the support protrusion portion to pass through.