The investigation of waveguide type submillimeter-wave (100 GHz-1 THz) antennas using Si wafers was performed. Si wafers were modified by the dry etching technique, followed by the through Si vias and Au films being deposited on the front, back, and the interior Si through a catalyzing process. The interior Si was used as the waveguide for the submillimeter-wavedevices. Using these modified Si wafers, two catalyzing processes were investigated, namely, a Sn-Pd process, and a self-assembled monolayer (SAM) process. In order to strengthen the adhesion force of the deposited films and the Si wafer, a Cr film was formed on both sides of the Si wafers. After the catalyzing process, electroless Ni deposited film was formed, followed by electrodeposited Au. It was confirmed that this structure worked as an antenna in the submillimeter-wave band.