Aim: This study aimed to examine the influence of state boredom on craving for smartphone use, as well as the potential moderating effect of individual differences - fear of missing out (FoMO). Methods: A total of 112 undergraduate students were randomly assigned to either low or high state boredom groups. Participants completed a reference copying task along with assessments for state boredom, craving for smartphone use, and FoMO. Results: The results indicated that: (1) Participants in the high state boredom group reported higher levels of background craving for smartphone use; (2) The FoMO moderated the association between state boredom and background craving for smartphone use significantly, which was stronger for individuals with a higher level of FoMO. Discussion: This study broadened the research by focusing on the influences of boredom and the mechanism of smartphone use craving and problematic phone use, which could provide guidance for the intervention of craving, and healthy smartphone use.  Kulcsszava: background craving for smartphone use, state boredom, fear of missing out, reference copying task, healthy smartphone use