Product or service quality refers to the perception of the degree to which a product or service meets customer expectations. The degree of customer satisfaction directly affects how the quality of a product or service is determined. The word quality is an abstract term and there are many ways in which it is interpreted. Today, quality is interpreted as value for the customer, respectively as a feature of a product or service that meets the needs of customers and determines their satisfaction. One of the goals of every company should be to increase customer satisfaction which also leads to increased profits. In that case, quality means profit. However, increasing or improving quality includes both financial investment and cost increases. Then quality means higher costs. Quality also implies the absence of omissions and errors that require repetition of a particular activity. This usually means loss of market share or customer, dissatisfaction of customers and partners, and loss of reputation. In this sense, this paper will deal with the quality management system in a production company with special reference to the application of quality management system in the department of technical maintenance of production lines and equipment. Full quality management directs companies towards comprehensive quality improvement of the entire organization. It applies to all persons and processes in the organization. This thesis describes how the application of the ISO standard, quality management and quality policy have a positive impact on a particular sector of the manufacturing company, the maintenance department, thus contributing to the overall quality and performance of the entire organization. The paper presents all the factors by which the maintenance department systematically improves the efficiency of the company as a whole. The maintenance process is described, the accompanying documentation is presented and the goals and results are highlighted. Proper management, employee involvement, process approach and continuous improvement are the main principles of quality management in the maintenance department. The aim of this thesis is to determine how quality management in only one sector, in this case the maintenance department, contributes to the overall improvement of the organization. Improving personal efficiency and monitoring of measurable data, as well as coordination and guidance of all members towards the set goals give positive results, which is confirmed by this thesis.