Since the participants of the stock market have a need for trust with a corporate governance codex supporting its development, the main issue of this thesis is the function of economical trust and corporate governance codices on the market transactions. The terms of trust, trustworthiness, and codex will be defined followed by a description of their respective economical conditions, features and meanings. Trust will be examined from the perspective of the new institutional economics while codices will be viewed from the perspective of corporate governance. The importance of reputation, sanction, reciprocity, and distrust as a cost driver in a trust relationship will be shown with the structural-individualistic scheme. The location and integration of trust and codices within an economic transaction relationship will be done according to the principal-agent theory.The aim of this master thesis is to analyze the relation between transaction relationship, trust relationship and codex relationship in a market context. The impact of the trust-based relationship on the behavior of transaction partners is the first objective. The next field of interest is the impact of a corporate governance codex on the trust between two transaction partners. This examination will be done by using the principal-agent theory. The impact of a codex-trust relationship combination on the transaction cost is the last objective of this work. The results are given by comparing it to a pure contract relationship based on the concept of the transaction cost theory.As a conclusion, three statements can be explained. Firstly, a trust relationship supports cooperative behavior with incentives. Secondly, a codex relationship has a positive impact on the emergence of trustworthy behavior. Finally, the combination of codex and trust mechanism as institutional arrangement has beneficial impact on the cost of transaction.