The article reveals certain problematic issues of criminal procedural legal relations between the investigator and the prosecutor. The purpose of the article is to study the problematic issues of the legal relationship between the investigator and the prosecutor in the modern conditions of reforming the criminal justice bodies and updating the current Code of Criminal Procedure of Ukraine. The beginning and course of the legal relationship between the investigator and the prosecutor is established by the current Code of Criminal Procedure of Ukraine and this cannot but affect the nature of their legal relationship. According to the general rule, the legal relationship of the investigator with the prosecutor begins from the moment of entering information into the EDPR It is proven that the nature of the legal relationship between the investigator and the prosecutor is negatively affected by the fact that the investigator is not the central and main figure of the pre-trial investigation, although he is responsible for the comprehensiveness, completeness and objectivity of the investigation of the circumstances of the criminal proceedings. It is emphasized that the current Code of Criminal Procedure of Ukraine does not clearly regulate the procedural status of the investigator, significantly narrows his powers and limits his independence in making procedural decisions, which in practice often leads to the delay of the pre-trial investigation and negatively affects its effectiveness. It is indicated that the nature of the investigator’s legal relationship with the prosecutor is also influenced by the fact that the investigator and the prosecutor are the subjects of evidence in criminal proceedings, but the prosecutor is endowed with powerful procedural powers in relation to the investigator under the current Criminal Procedure Code of Ukraine. The prosecutor supervises the observance of laws during the pre-trial investigation in the form of procedural guidance of the pre-trial investigation.