Temperature and humidity dependency on electrical resistivity are discussed using sandstone (SS) and marble (MB) for porous samples and tempered glass (TG) for nonporous sample. A total of 54 experiments has been performed; 3 samples, 3 temperature conditions of 15, 25, and 35℃, 3 relative humidity conditions of 45, 65, and 85%, and 2 different initial conditions of dry and wet. Resistivity changes have been monitored for 10 hours by a voltmeter-ammeter method. Asymptote equation is successfully applied to the resistivity change for both dry and wet initial conditions simultaneously, which allow us to determine unique resistivity on a specific temperature and relative humidity. For TG sample, stronger resistivity changes can be observed by temperature change rather than relative humidity change, while vise versa for porous SS and MB samples, which means that even very small porosity of 0.42% and 0.74%, respectively, affects the resistivity with temperature and relative humidity changes.