A reformed fuel manufacturing apparatus and method is provided, including a water treatment unit configured to pretreat a water introduced therein by using a carbon filter and a reverse osmosis purifier, an electrolysis tank unit connected to a reverse osmosis purifier and configured to additionally pretreat the water, an oil tank unit configured to store an oil introduced from an oil inlet, a mixed oil unit connected to the water treatment unit and the oil tank unit and configured to produce a mixed oil by using an inline mixer, and an ionization catalyst unit connected to the mixed oil unit and configured to convert the mixed oil to a reformed fuel; and a control unit configured to control all electronic and mechanical actuations of the reformed fuel manufacturing apparatus.