Selective laser melting technology is one of the types of additive manufacturing in which the product is created by layer-by-layer melting of metal powder using a laser beam that moves along a predetermined path according to a three-dimensional model. Product quality significantly depends on the process parameters. According to the literature, it is known that the minimum number of pores can be achieved with a specific volumetric energy of 40–280 J/cm$^3$. Establishing optimal process conditions is an urgent task that requires a comprehensive, scientifically sound approach. The aim is to establish the influence of the specific volumetric energy level and the method of its provision on the porosity and microstructure of parts from the heat-resistant Insonel 718 alloy. The experiments are carried out with varying process parameters to change the specific energy density and at a constant energy level with different values of laser power and scanning speed. Porosity is evaluated by microstructural image analysis using optical microscopy (Carl Zeiss AXIOVERT 200M). The experimental results are discussed with respect to the formation of porosity and microstructure of the experimental bulk samples. The optimum level of specific volumetric energy needs to create a product with a minimum porosity on a 3$D$ Alfa-150 printer (ALT Ukraine LLC) from Inconel 718 alloy, which is 40 J/cm$^3$ with a layer thickness of 50 $\mu$m, is established. A found, at a constant energy level and different powers (80–250 W) and scanning speed (400–1000 mm/s), the best results in the experiment are obtained at higher power and scanning speed. This is explained by the fact that with a higher laser radiation power, a stable track can be obtained in a wider range of scanning speeds.