Manager ethics or ethical behaviour of the manager is the most important condition for the company to successfuly make business or be of use to any wider social community. When we´re talking about manager ethics, we`re actually talking about manager behaviour which should follow the norms of human rights, solidarity and respect of the laws while doing business. The main way that unethical manager behaviour happens is corruption, from which come all the other types of unethical behaviour in business, they are harmful to society and disrupt the core societal values. Unethical manager behaviour happens when the manager, for personal benefit, disregards the interests that he is supposed to protect regarding to laws jurisdiction which he has while managing a business. There also exists individual corruption which is present in all aspects of human functioning, it`s the most widespread while institutional corruption affects the downfall of values in our society because it causes fear and falterinf of morale in most citizens. The most widespread types of corruption are giving and receiving bribes, doing business without a conscience and illegal business. Stopping corruption is a task in every business on all levels of managment, but the most important part is establishing internal controls. Internal controls have the task to monitor business and stop corruptional behaviour. In the last ensemble of the paper, we`re going to introduce ourselves to the way of establishing internal control in the company Plovput with the task to secure ethical business of this public firm.