The epoxy resin used in this study is modified with 5 wt% of polyaniline. Then electrically conductive modified epoxy resin (MER) (as matrix) and different weight amounts (10–30 wt%) of andesite waste (AW) as filler are mixed together to obtain the andesite waste-reinforced epoxy resin composites. The effects of filler amount on the electrical and ultrasonic properties of the modified epoxy resin are examined. The effects of AW amount on the ultrasonic properties of the obtained MER/AW composites are investigated by ultrasonic pulse-echo method. The conductivity of the composites is measured by a four-point probe (FPP) method, and the morphologies of the samples are investigated by scanning electron microscopy (SEM). Experimental results show that increasing the amount of AW causes a linear increase in the elastic properties. On the other hand, the same amounts of AW decrease the electrical conductivity of MER.