We developed an agar phantom as a muscle equivalent phantom which is applicable to 13.56MHz RF-induced hyperthermia. The phantom is composed of 2.0 w/w % agar, 0.43 w/w % NaCl, and 97.57 w/w % water. The electric conductivity is 0.83Ω/m at 22℃. The specific dielectric constant is 109 at the same temperature. Reference is made to the electric conductivity and the specific dielectric constant of the muscle at 37℃ which are 0.83 Ω/m and 112, respectively.