Background: Physical, emotional, psychological, and social factors influence the high level of burden of a caregiver providing care for a patient at home after a stroke. The purpose of this study was to identify and evaluate factors influencing the high level of burden on the caregiver providing care for a post-stroke patient, including factors on the part of the patient and caregiver. Methods: This cross-sectional study was conducted at the Neurological Rehabilitation Department of the Hospital Beskid Treatment and Rehabilitation Complex in Jaworze, Poland, and the Neurological Rehabilitation Department of the Railway Hospital in Wilkowice-Bystra. The study participants comprised post-stroke patients and their family caregivers (during visits to hospital), 110 pairs. The measures for caregivers were such as the following: Beck Depression Inventory, the Polish adaptation of the Perceived Stress Scale, the Polish adaptation of the Mini-COPE questionnaire to measure stress coping strategies, and the WHO Quality of Life Brief Version. The measures for patients were such as the following: the modified Rankin Scale and Abbreviated Mental Test Score to assess functional capacity for simple Activities of Daily Living (ADL). All statistical calculations were performed using the R statistical package version 4.4.2. Results: A high caregiver burden was found in 30 people (27.3%). Logistic regression analysis proved that low quality of life, stress, caregiver-triggered strategies (discharge and cessation of activities), caregiver frustration, psychological burden, financial situation, longer time spent on patient care, functional status (ADL) on the part of the patient, judgment of significant degree of disability judgment, and age of the patient are determinants affecting high caregiver burden levels. Conclusions: Almost 1/3 of caregivers experienced a high burden when taking care of a person after stroke. Analyzing the Gini index, from the model's point of view, quality of life is the most important characteristics, and caregiver frustration is the least important, which influences the high level of caregiver burden.