Washing machine

The invention provides a washing machine capable of adding a detergent according to needs. A washing machine according to an embodiment is provided with: a washing tub for accommodating laundry; a detergent feeder for automatically feeding a detergent into the washing tub; a control unit that controls the detergent feeder; and a soiling degree detection unit that detects the soiling degree of thewashing water in the washing tub and inputs a detection signal to the control unit. The control unit monitors the detection signal during the washing operation and finds the rate of change of the soiling degree at least twice, and when the difference between the obtained rates of change exceeds a predetermined value, adds a detergent to the detergent feeder. 本发明提供一种能够根据需要追加投入洗涤剂的洗衣机。实施方式的洗衣机具备：洗涤桶，收容洗涤物；洗涤剂投入器，向洗涤桶内自动地投入洗涤剂；控制部，控制洗涤剂投入器；以及脏污度检测部，检测洗涤桶内的洗涤水的脏污度，向控制部输入检测信号，控制部在清洗运行中监视检测信号，并至少两次以上求出脏污度的变化率，在求出的变化率之差超过规定值时，使洗涤剂投入器追加投入洗涤剂。