The objective of this paper is to analyze Heidegger’s various existential modes of Dasein as being with others(Mitsein), and for this I examine. “solicitude”(Fürsorge), one of the main existentialia that Heidegger claims in Being and Time. The analysis is a preliminary study to pursue the ethical implications in Heidegger’s fundamental ontology, which I argue remains post-ethical within its primordial origin. According to Heidegger, Dasien has different attitudes towards things and other Dasein. The former is “concern”(Besorge) and the latter is solicitude. Various modes of solicitude form a continuous spectrum from the positive poles, but Dasein proximally and for the most part shows a lack of solicitude towards Dasein-With, which Heidegger also calls ‘concernful solicitude’ as the attitude of ‘das Man’. In this way Heidegger elucidates the facticality of Mitsein, where Dasein misleads solicitude to concern, thus not treating others through solicitude but with concern. In this phenomenological possibility Dasein-With is not considered as an entity whose ‘Wesen’ is existence but as things, i.e. a non-Dasein entity. Heidegger does not advance this mode of solicitude, and by not doing so he prevents his analysis of solicitude from developing into an ontical inquiry that deals with questions in relation to ethical values. However, if we investigate the negative pole of this mode of solicitude, and reconstruct the whole continuum of the solicitude spectrum from positive to negative, the phenomenological status of Dasein’s misleading of solicitude emerges. I argue that this status is what Heidegger intends to hide so as to maintain his fundamental ontology as primordial and so post-ethical. By paying a close attention to this negative status of solicitude, which Heidegger does not attempt to emphasize, I suggest that the phenomenological study on the negative pole of solicitude as Dasein’s everyday mode of being with others should be a starting point for the post-metaphysical inquiry for ethics that restores the crucial questions around ethical values today.