Objectives: This study aims to evaluate the costs of informal care for children with neuromuscular disease and evaluate how physical and psychological health is associated with socio-demographic variables. Methods: A cross sectional design was used with a convenience sample of 110 carers that participated in this study. Participants were recruited from Spanish hospitals and rare diseases organizations. Economic costs and sociodemographic aspects were assessed using the economic costs questionnaire and the sociodemographic questionnaire. Physical and psychological health was evaluated using the CarerQol-7D, PHQ-15, Barthel Index, Zarit Overload Scale and Satisfaction with Life Scale. Results: Carers of children with neuromuscular disease spent a large percentage of their annual income in physical therapy, psychological care and speech therapy. Informal costs differed according to the degree of dependency of the child. These were higher in those caregivers whose child under their care presented low functional independence. The loss of work productivity was related to marital status, use of professional services and the child’s dependency. Finally, carers who were female, single or separated and without a job showed worse physical and psychological health. Conclusions: The results highlighted that carers have to face a number of high costs because of the non-existence of social protection and due to the child’s diagnosis.