This study examines the flexural strength and compressive strength of the mortar, which were mixed with electromagnetic field treated water (EMFTW) and contained fly ash. EMFTW was obtained by passing tap water through an electromagnetic field. The test variable is the fly ash content in place of cement and the water treated with EMFTW in place of tap water. The results show that the flexural and compressive strength of the mortar samples mixed with MFTW is 12.56% and 15.8% higher than that prepared with tap water, respectively. It is also found that magnetized water improves the resistance to bending and compression by 12.67% and 4.35% to that prepared with tap water and 10% fly ash instead of cement.