This study aimed to clarify perspectives of bereaved family members regarding opioids and compare perceptions before admission and after bereavement. A cross-sectional questionnaire survey for bereaved family members in 100 inpatient palliative care units was administered. Participants were 297 bereaved family members of patients who used opioids. Many bereaved family members had misconceptions of opioids before admission. There was improvement after bereavement, but understanding remained low. Respondents less than 65 years old showed significantly greater decreases in misconceptions regarding opioids compared to older generations, after bereavement. Bereaved family members who were misinformed about opioids by physicians were significantly more likely to have misconceptions about opioids. Educational interventions for physicians are needed to ensure that they offer correct information to the general population.