This study aimed to evaluate the reduction of total, organic, and inorganic arsenic content in (hijiki). Initially, the six most common arsenic compounds in hijiki and its organs were evaluated, among which only arsenate and arsenobetaine were detected. Thereafter, the entire plant, including the stalk and leaves, was treated with heat and NaCl solution, individually and in combination. Heating at 90 °C for 5 min significantly reduced arsenic content in hijiki by approximately 33-80%. Treatment with NaCl solution significantly reduced arsenic content in hijiki, except for arsenobetaine content in the stalk. Combinatorial treatment further decreased arsenic content by more than 5-20%. In conclusion, consumption of hijiki after boiling at 90 °C and soaking in 2% NaCl solution reduces the intake of inorganic arsenic by consumers.