Rheological properties of the mixture of gelatin and agar, such as viscosity and elasticity, are affected by the mixing ratio of gelatin and agar, pH, type of gelatin, ionic strength, and so on. In this study, we measured the dynamic viscoelasticity and the turbidity of the mixture over a wide pH range. Furthermore, the same measurements were carried out also at a high ionic strength. Gelatin and agar were completely dissolved in Good's buffer by using an autoclave at the concentrations of 8% and 1.5%, respectively. The mixture formed a transparent and weak gel at pH below the pI of gelatin, while it formed an opaque and elastic gel at pHs above the pI of gelatin. Large effects of ionic strength on the viscoelasticity and the turbidity for the mixture were observed at pH not greater than gelatin's pI.