The Bi-based oxide superconducting wire is one of the most promising materials for practical uses such as electric power transmission, electromagnets and so on. For the higher performances required in these applications, it is necessary to increase the critical current (Ic). We have carried out synchrotron radiation X-ray diffraction analysis to improve our manufacturing processes and thus to achieve higher Ic. We have performed in situ X-ray diffraction measurements during the sintering and cooling processes, and observed the decrease of Bi-2223(=(Bi,Pb)2Sr2Ca2Cu3Ox) phase during the cooling process. We have also evaluated the distribution of the crystal orientation in whole wire thickness, by measuring the rocking curves. We have observed that the distribution of the crystal orientation is improved by a refinement of the process conditions.