controller re determines a heating rate of the heater a blowing rate and speed of the blower rotation speed of the drum a drying time period and the like depending on the extent of dryness of the drying object in the drum 20 and controls the dryer that is if the extent of drying progress of the drying object is later than expectation after drying the drying object for a certain time period the heating rate of the heater the blowing rate of the blower rotation speed of the drum and the like are increased for fast drying opposite to this if the extent of drying progress of the drying object is faster than expectation after drying the drying object for a certain time period the heating rate of the heater the blowing rate of the blower rotation and speed of the drum are decreased for slow down of the drying upon completion of the drying the sensor 200 senses it and the controller stops operation to prevent unnecessary excessive operation in advance thus the dryer of the present invention having the optimal feed back system always permits to progress an optimal drying and reduce a drying time period and energy consumption by using the foregoing principle in the meantime the device of the present invention having the sensor 200 which can sense information on an inside of the drum 20 provided thereto is applicable not only to the dryer but also to a drum type washing machine having a drying function.