Aim Febrile residents in long‐term care facilities (LTCF) might be inadequately evaluated by caregivers. The present study aimed to examine the factors associated with inadequacy of initial fever evaluations by caregivers at night in LTCF. Methods We carried out a cross‐sectional study among a convenience sample of caregivers employed at 11 LTCF in Japan using a vignette‐based questionnaire. The respondents were randomly assigned to one of two scenarios describing a mild or severe febrile episode in an LTCF resident at night. The respondents’ thinking patterns were classified based on influential factors in their fever evaluation. Associations between adequacy of evaluation and respondents’ characteristics were evaluated using generalized linear mixed models. Results A total of 34% of fever evaluations among caregivers were considered to be inadequate regarding the necessity for examination by a physician, due in most cases to underestimating the severity of the fever. Respondents’ thinking patterns in fever evaluation were significantly associated with the adequacy of the evaluation. Caregivers who placed particular importance on the preferences of residents and families versus other factors including the resident's febrile condition, were more likely to make an inadequate evaluation than those who did not. Conclusions Our findings here suggest that eagerness to comply with residents’ preference in fever evaluation could prompt caregivers not to call for an appropriate diagnostic procedure. Geriatr Gerontol Int 2017; 17: 1294–1299.