The aim of the article is in clarification of the concrete correlation between the first two constitutive moments of the structure of the being-in-the-world pointed by Heidegger in his ontology. Namely, we deal with the connection of the worldhood of the world and the Self of the one, who exists in the world. We used the following methods: textological analysis, benchmarking analysis, interpretation, generalization, epagoge. The results of this investigation are the following. (1) We detected that Heidegger treats the world primarily as a totality of the involvement, which only makes the usage of the entities as ready-to-hand possible. (2) We found that the understanding of the world as totality of the involvement is insufficient for the treatment of the world as such in Heidegger. It must be supplied by the notion of the world as unity of the horizon of the transcendence of a human being. The first notion of the world is derivative from the second one in Heidegger’s ontology. (3) We showed that the Others cannot be reduced to the entities of the environment, but they are given primarily to a human being from the perspective of the environment. (4) We grounded that it is necessary to allow the world as unity of the horizon of the human transcendence, which is out of the totality of the involvement, for the understanding of the Others as Others to be possible. As conclusion, we pointed the reasons why the world both as totality of involvement and as unity of the horizon of the transcendence cannot be finally deformalized in the ontology of Martin Heidegger.