Eco-friendly materials, such as alternative vegan materials using various fungal resources, are being actively researched to reduce environmental pollution and facilitate a healthy lifestyle. The fungal mycelium-based mushroom mycelium mat is one such emerging material. In this study, the commonly used mushroom mycelium culture method was modified to reduce the time required to produce the mycelium mat, lower the possibility of contamination, and improve the properties and quality of the mat. Shortening the period required for the previously used primary bag culture and secondary mat production culture. A culture method in which the bag culture was omitted was attempted using a mycelium mutated by gamma irradiation to the mycelium of Trametes orientalis. In addition, various nutrients were added to the fungal solution to observe the change in physical properties of the fungal mat. High-quality mycelium mats were produced in the experimental group containing 1.5% CaCO3 in sawdust medium, and the period was also reduced by more than 10 days compared to the existing production method. In the future, for mass producing mycelium mats, additional selection of medium components and optimization of culture conditions are essential.