32 the cpu 40 determines whether the microcapsule sheet 11 is out of stock in the cartridge c if it is determined that the microcapsule sheet 11 is not out of stock the copying operation is continued in step 2 s2 on the other hand if it is determined that the microcapsule sheet 11 is out of stock the pressure roller 13a of the pressure developing unit 13 is moved away from the backup roller 13b in step 3 s3 thereafter the take up shaft 15 is rotated in step 4 s4 to wind up a tail portion of the microcapsule sheet 11 in the cartridge c and the lamp 39 in the display unit 38 lights up for indicating that the microcapsule sheet 11 is out of stock in step 5 s5 further in a step 6 s6 on the basis of the cartridge exchange signal outputted from the sensor 36 the cpu 40 determines whether the inner cover 35 is opened if it is determined that the inner cover 35 is opened it is subsequently determined whether the heat roller 20a is in the on state in step 7 s7 on off detector 50 provides cpu 40 with the information regarding whether heat roller 20a is turned on if.