A wireless wearable device that operated by Android phones to measure and record the skin moisture of human face is proposed in this paper. The skin moisture of human face is measured as a resistance by a simplified Electrochemical Impedance Spectroscopy. The interdigital electrode is used to contact skin directly, and also conducts square wave signal to skin surface. However, skin moisture attenuated the detected signal differently, which is regarded as the change of impedance of skin. This study also proposes a conversion formula from output voltage of interdigital electrode to skin moisture. Android phone performs the conversion from voltage to skin moisture, stores and shows the percentage of moisture on screen simultaneously. In summary, this wearable tester feature demonstrates a low-cost, but relatively accurate measure of moisture of skin, and it is shown potentially usful in individual skin care.