PURPOSE: To prevent jams from occurring without not so large load being exerted to conveyance of a sheet material, by setting the conveying speed of an upstream conveyer means so that it is faster than that of a downstream conveyer means.

CONSTITUTION: A nonlinear section 5 is composed of guides 15W18, and a transfer paper sheet fed by an upstream conveyer means 1 in the direction (a), is introduced into the nonlinear section 5. The transfer paper sheet is conveyed into a loop section 4 after passing through a gap 3 between the guide plates 15, 18, and is discharged in the direction (b) by means of a conveyer means 2 positioned at the outlet of the nonlinear section 5, after passing through a gap 3 between the guide plates 17, 18. Since the conveying speed of the conveyer means 1 is previously set so that it is slightly higher than that of the conveyer means 2, no surface-to-surface contact which otherwise offers a large resistance is generated between the guide plates and the transfer paper and thereby it is possible to smoothly convey the transfer sheet.