A recording medium supply device includes a cassette attachable to and detachable from a main body and capable of stacking recording medium thereon, a feeding roller which feeds the uppermost recording medium to the main body from a leading end of the recording medium, a regulating member which is arranged forward in the direction in which the cassette is removed from the main body as seen from the feeding roller, and a projection preventing member attached adjacent to the tip portion of the cassette facing the leading end of the recording medium. The position of the lower end of the regulating member is higher than the cassette attached to the main body, and lower than the lower end of the feeding roller, and the position of the upper end of the projection preventing member is higher than the position of the lower end of the regulating member.