In the present study, we examined the effects of ionic strength and temperature for adsorption of tetrakis-N-methylpyridyl porphyrin (TMPyP) on mesoporous silica with 7.0 nm in pore diameter. The adsorption of TMPyP in 10 mM phosphate buffer solutions containing 0–150 mM NaCl showed linear adsorption isotherm plotted as inverse of the adsorption amount of TMPyP versus inverse of the equilibrium solution concentration of TMPyP. From the analysis of the adsorption isotherm by electrostatically modified Langmuir model, decrease in apparent adsorption constant with increasing the ionic strength was ascribed to the surface charge screening by electrolyte ions. In the temperature dependence on the TMPyP adsorption, non-linear van’t Hoff plots were analyzed by including heat capacity change during adsorption. The results of the van’t Hoff analysis indicated that the TMPyP adsorption at low temperature was exothermic and enthalpy-driven reaction, whereas it became endothermic and entropy-driven reaction with temperature elevation. In addition, the surface diffusivity was suggested as a primary factor to govern the maximum adsorption amount of TMPyP on mesoporous silica.