This paper describes a novel experiment in which alumina was joined using polycarbosilane (PCS) and an aluminum foil. PCS was used to design the surface structure of alumina, and the aluminum foil enabled the formation of an area that included the alumina surface designed using PCS; this area could be joined to ceramic materials. A four-point bending test revealed that the flexural strength of both the silicon carbide (SiC) and the silicon oxide (SiO₂) pieces that were obtained from alumina whose surfaces were modified to SiC or SiO₂ increased, compared with the flexural strength of ceramics joined by alternative methods involving the use of organometallic polymers whose compositions are similar to SiC and SiO₂. Moreover, it was apparent that alumina was formed by the reaction of SiO₂ with aluminum. However, traces of Al and Si remained in the joining area in both the SiC and SiO₂ pieces.