Personal tempos in our rhythmic movements have been studied with various tasks. However, no studies have examined the personal tempo in bimanual coordination with interference between the right and left hand movements, because the previous studies used auditory or visual stimuli in acquisition. For the same reason, a formation of the bimanual coordination pattern could not be examined. Therefore, the purposes of this study were to compare personal tempos produced by a single-rhythmic tapping and a 3 : 2 polyrhythmic tapping, and to clarify a mechanism of the 3 : 2 polyrhythmic pattern formation from a viewpoint of entrainment. Intertap intervals (ITIs) of each rhythmic tapping by ten subjects were analyzed. Results showed that the single-rhythmic tapping produced ITIs which were similar to ITIs of 3-beat sequence in the 3 : 2 polyrhythmic tapping. This suggests that there exist consistency between the single-rhythmic tapping and polyrhythmic tapping with a personal tempo. Another result showed that 2 : 1 and 1 : 1 patterns were emerged before the formation of 3 : 2 pattern. Such a shift is expressed in Farey tree that shows frequency rations at entrainment. We found that the complicated pattern was formed through the formation of more stable patterns formed by entrainment.