This study aimed to explore the relationships among autism spectrum disorder (ASD) traits, loneliness, and social networking services (SNS) use. We created a questionnaire to evaluate manners during LINE use, which included five factors: "low literacy," "inactive use," "low responsiveness," "lack of consideration," and "low group activity." Structural equation modeling revealed that difficulties in attention switching and low communication skills were associated with low literacy, low social skills were associated with inactive use, and low literacy and inactive use were associated with loneliness. We suggested that SNS use plays a role in maintaining and enhancing friendships, whereas college students with higher ASD traits tend to use inappropriate manners for SNS, which is associated with loneliness.