This study aimed to investigate the relationship between sensation seeking, loneliness, and cyberspace addiction among female high school students in Qazvin city. The statistical population of this study included all female high school students in Qazvin city, 8067 students in 1403-1404. For this purpose, 369 female high school students in Qazvin city were selected based on the Morgan table. Students were selected using the convenience sampling method. Data were collected using the Russell, Pilva, and Cortona Loneliness Scale (1980), Young's Cyberspace Addiction Questionnaire (1998), and Zuckerman's Sensation Seeking Questionnaire (1978) and analyzed using Pearson's correlation test and regression test. The results showed that there is a significant relationship (P<0.01) between the components of sensation seeking, experience seeking, inhibition avoidance, and boredom susceptibility, and loneliness with cyberspace addiction. According to the results obtained, it can be concluded that as feelings of loneliness and excitement seeking increase, the level of cyberspace addiction also increases.