erahertz (THz) communications is expected to be an essential part of the future mobile communication system to meet the demand for ubiquitous high-speed data transmission everywhere. To overcome the limitations of THz communications, reconfigurable intelligent surface (RIS) shows their great potential. THz indoor channel measurements were performed using 1-bit and 3-bit passive-RIS fabricated as a passive reflector engraved on the PCV panel designed for a fixed angle of incidence and reflection to understand the propagation channel including RIS. A part of the initial assessments for the THz channel measurement including RIS are presented in this paper.