This study proposed some considerations for designing social media to encourage self-reflection of users, referring to rationales of exemplary case, --Ripening Room?. Ripening Room provides ripening time, a delay period between the time of writing and sharing posts, and a ripening score to evaluate users' self-reflection. To give insights for the design a preliminary exploration was conducted on university students about their perceptions and experience of self-reflection in social media. To evaluate the effect of Ripening Room's design, an empirical study on Ripening Room was conducted. Participants mentioned that the features of Ripening Room inspired them to self-reflect upon their thoughts, emotions, and behaviors. From the findings of the empirical study, further implications were suggested.