Several solvents with different dielectric constant were used for electrode preparation of direct methanol fuel cell (DMFC). When the Nafion® solution was mixed with various kinds of solvents, the mixture changed into one of three states such as solution, colloid, and precipitate. The changes in catalyst layer structure due to those states made performances and characters of single cells different. According to impedance spectra of each anode, the differences in mass transfer resistance were related to performances of single cells. Conditioning time increased with the decrease of dielectric constant of solvent. Particularly, in case of dipropyl ketone (ε=12.60) conditioning time increased by about 2 times and performance by more than 20% in comparison with isopropyl alcohol (ε=18.30).