A transfer type electrophotographic copying apparatus with a reciprocating platform to place an original to be copied thereon, which comprises a rotatable photoreceptor drum of a small diameter, and processing devices of small size disposed around the photoreceptor drum with minimum spaces necessary between the processing devices, so that the size and weight of the copying apparatus can be reduced to a large extent. The housing of the apparatus can be divided into an upper frame and a lower frame with the upper frame pivotally connected to the lower frame for easy access to the internal mechanisms in maintenance and replacing of the parts.