Dopamine contributes to attention as a key neurotransmitter in the nervous system projecting to the forebrain. Numerous animal models have been generated to model attentional impairment with dopaminergic dysregulation. We previously generated mice lacking Shati, an N-acetyltransferase-8-like protein, on a C57BL/6J genetic background (Shati/Nat8l^−/−). Modulation of this gene leads to changes in behavioral phenotypes such as attentional impairment associated with hypodopaminergic neurotransmission in mice. In this study, the effect of Shati/Nat8l deficit in dopaminergic projections was investigated using an object-based attention test (OBAT). Shati/Nat8l^−/− mice showed attentional impairment in the OBAT, accompanied by reduced neuronal activity in the prefrontal cortex (PFC) and the hypodopaminergic function indicated by the reduced expression of tyrosine hydroxylase (dopaminergic marker) protein and dopamine-related genes in the ventral tegmental area (VTA). The activation of dopaminergic projections of the VTA-PFC by chemogenetic stimulation ameliorated the attentional impairment in Shati/Nat8l^−/− mice. These results confirm previous findings that Shati/Nat8l deficiency interrupts the dopaminergic system and contributes to novel evidence that Shati/Nat8l is implicated in the dopaminergic projections of the VTA-PFC, which play important roles in the regulation of attention in the OBAT.