This cross-sectional study aims to determine the level of subjective burden and anxiety of caregivers of dependent older relatives that start providing care in the hospital and to analyse the relationship between objective burden, subjective burden and anxiety in these caregivers. Seventy-two caregivers of dependent older relatives were recruited in a medium–long stay hospital. Sociodemographic variables, number of basic activities of daily living (ADLs) attended, hours of surveillance, burden, and anxiety were collected from caregivers. A trajectory analysis was used to analyse the relationship between variables. Of the caregivers, 36.1% had subjective burden and 14.9% had anxiety. Subjective burden was positively associated with the number of basic ADLs attended, the hours of surveillance, and the cognitive impairment of the care recipient. Anxiety was also positively associated with subjective burden. Subjective burden mediated the effects of the number of basic ADLs attended, hours of surveillance and the cognitive impairment of the care recipient on anxiety. The levels of subjective burden and anxiety in caregivers debuting in hospital care are elevated, showing the need for these caregivers to be cared for. Subjective burden is a possible risk factor for anxiety, independent of the objective burden; it may buffer the effects of objective burden on anxiety.