Method of manufacturing an element chip which can suppress residual debris in plasma dicing. A back surface of a semiconductor wafer is held on a dicing tape. Then, a surface of the wafer is coated with a mask that includes a water-insoluble lower mask and a water-soluble upper mask. Subsequently, an opening is formed in the mask by irradiating the mask with laser light to expose a dividing region. Then, the semiconductor wafer is caused to come into contact with water to remove the upper mask covering each of the element regions while leaving the lower layer. After that, the wafer is exposed to plasma to perform etching on the dividing region exposed from the opening until the etching reaches the back surface, thereby dicing the semiconductor wafer into a plurality of element chips. Thereafter, the lower layer mask left on the front surface of the semiconductor chips is removed.