A magnetic resonance coil has an antenna portion for accommodating a body part to be examined, the antenna portion is formed by a number of constituent units connected in series, the positions between various constituent units are relatively movable. By moving the positions between the constituent units, a portion of the area between at least two constituent units overlaps. By increasing or reducing the number of the constituent units, or by adjusting the overlapped area between the constituent units, one pair or a number of pairs of the constituent units are made to overlap completely, so as to achieve the adjustment of the size of the antenna portion to accommodate a body part to be examined, and to make said antenna portion as close as possible to the body part to be examined, so as to obtain a signal with a relatively high signal-to-noise ratio, and to obtain a relatively high imaging quality.