In this study, the relationship between representative injection molding conditions and joining strength was investigated in injection molded parts joined with metal and resin using an aluminum plate with the uneven surface. Moreover, visualization observation of resin flow into the fine uneven part on the metal surface was carried out, and the injection molding conditions for enhancement of joining strength were proposed. The results of the experiment indicated that the joining strength of injection molded parts joined with metal and resin is improved, when injection rate, resin temperature or mold temperature are high. From the result of visualization experiment during injection molding, it was inferred that the joining strength was improved because the resin flows into the uneven part before the solidification layer grows. For the improvement in joining strength of injection molded parts joined with metal and resin, it was concluded that high filling speed is essential to make growth of the solidification layer delayed.