A dirt removing device (100; 110; 120), for washing a local part of a cloth, comprising: a cassette mechanism (1; 10; 20), the cassette mechanism (1; 10; 20) comprises a head (5; 8; 11) formed with a beating surface, a water accommodating portion (7; 12; 212) for accommodating water, and a water supplying passage (6; 6'; 13) which is started from the water accommodating portion (7; 12; 212) and penetrates into the entire head (5; 8; 11); characterized by further comprising: a device body, the device body comprises a vibration unit, wherein the cassette mechanism (1; 10; 20) is detachably received in the vibration unit, and the vibration unit, when being powered, causes the cassette mechanism (1; 10; 20) to vibrate in a direction substantially orthogonal with the beating surface of the head (5; 8; 11), wherein the water is supplied from the water accommodating portion (7; 12; 212) to the beating surface of the head (5; 8; 11) through the water supplying passage (6; 6'; 13), along with the vibration of the cassette mechanism (1; 10; 20) caused by the vibration unit, wherein the vibration unit comprises a motor, a first gear, a second gear, a third gear, a cylinder body, and a coil spring; the motor of the vibration unit is powered by a battery to rotate, and the rotation is transmitted to the third gear through the first gear and the second gear after being decelerated, when an engaging projection (44b1) of the third gear is engaged with an engaged claw 45b1 of the cylinder body, the cylinder body and the cassette mechanism (1; 10; 20) are lifted together by a specified size, and when the engaging projection (44b1) of the third gear is disengaged from the engaged claw (45b1) of the cylinder body, the cylinder body and the cassette mechanism (1; 10; 20) are ejected by the elastic force of the coil spring and the head (5, 8,11) beats a dirt portion (Sp) of cloth. a device body, the device body comprises a vibration unit, wherein the cassette mechanism (1; 10; 20) is detachably received in the vibration unit, and the vibration unit, when being powered, causes the cassette mechanism (1; 10; 20) to vibrate in a direction substantially orthogonal with the beating surface of the head (5; 8; 11), wherein the water is supplied from the water accommodating portion (7; 12; 212) to the beating surface of the head (5; 8; 11) through the water supplying passage (6; 6'; 13), along with the vibration of the cassette mechanism (1; 10; 20) caused by the vibration unit, wherein the vibration unit comprises a motor, a first gear, a second gear, a third gear, a cylinder body, and a coil spring; the motor of the vibration unit is powered by a battery to rotate, and the rotation is transmitted to the third gear through the first gear and the second gear after being decelerated, when an engaging projection (44b1) of the third gear is engaged with an engaged claw 45b1 of the cylinder body, the cylinder body and the cassette mechanism (1; 10; 20) are lifted together by a specified size, and when the engaging projection (44b1) of the third gear is disengaged from the engaged claw (45b1) of the cylinder body, the cylinder body and the cassette mechanism (1; 10; 20) are ejected by the elastic force of the coil spring and the head (5, 8,11) beats a dirt portion (Sp) of cloth.