Recently, mobile phones have been downsized increasingly and the antenna is embedded inside. In general, the characteristics of the antenna are influenced by a body of user. The influence of the hand on mobile phone is considered to be very important in designing the antenna. So far, the influence of the hand on the antenna has been investigated by use of a hand phantom, which has same electrical properties as the body and a particular shape. In this study, the authors have developed a hand phantom which can change its shape arbitrarily. Moreover, the S-parameter of the antenna gripped by the developed hand phantom was measured to show the effectiveness of the developed hand phantom. I TRODUCTIORecently, mobile phones have been downsized increasingly and the antenna is embedded inside. In general, the characteristics of the antennas are influenced by a body of user. The performance measurement of mobile phones antennas are commonly carried out in laboratories with head-shaped phantoms. However, recent studies showed that the presence of the hand in vicinity of mobile phones has more effects on the antenna performances rather than head [1], [2]. Hence, the influence of the hand on mobile phone has been recognized to be very important [3]. So far, the influence of the hand phantom on the antenna has been investigated developing an imitation of a human hand, which has its electrical characteristics and a particular shape [4], [5]. However, in fact, the hands-shape changes in different situations when we use a mobile phone. In numerical calculation, it is easy to change a shape of hand model by changing the parameters. However in the measurement, it is not easy to change a shape of a hand phantom, and it's commonly needed to alchemize the hand phantom in order to evaluate the influence of the hand phantom in divers ways on mobile phone. Then, there are few reports developing a hand phantom which can change its shapes. In this paper, we developed and investigate a hand phantom which is suitable for such purpose. In order to confirm the effectiveness of our developed hand phantom, input impedances of the antenna in the situation of the developed hand phantom gripping a mobile terminal, was measured. ELECTRICAL PROPERTIES A D A SHAPE OF HA D PHA TOMIn this paper, target frequency of the investigation is 2.0 GHz, which is one of the frequencies for 3G mobile communication system. The target values of dielectric properties are set to be skin-equivalent at the frequency. Table 1 shows the composition of skin-equivalent solid phantom employed in this research [6]. The measured electrical properties of the skin model are shown in Fig. 1. According to Fig. 1, the electrical properties of the fabricated phantom are ε r = 40.2 and σ = 1.41 S/m. The target value of electrical properties of the phantom are ε r = 41.0 and σ = 1.30 S/m. It is clear that the measured relative permittivity and conductivity are within ±10% difference of the target values. There is no influence on the antenna performances with such different errors. Th...