A chemical protective airtight suit for accommodating a self-contained breathing apparatus comprising: a body portion for covering the part of the human body extending from the chest to the abdomen, a head portion for covering the part of a human body extending from the top of the head to the neck, which has a slanted rear side extending downward and rearward toward the rear side of the body portion opposing a high pressure air vessel accommodated in the chemical protective airtight suit, a pair of arm portions for covering the parts of the human body extending from the shoulders to the wrists, and a pair of leg portions for covering the parts of the human body extending from the abdomen to the calves, the aforementioned portions being integrated in a unitary body, and cooperating with a pair of gloves (α) for covering the parts of the human body extending from the wrists to the fingers and a pair of foot portions (β) for covering the parts of the human body extending from the calves to the toes so as to protect the whole human body, characterized in that the chemical protective airtight suit further comprises a vertical partition (11 b) accommodated in the head portion and fixed to the top of the head portion at the upper end and to either side of the head portion at either side end so as to divide the internal space of the head portion into a front portion for accommodating the head of the human body and a rear portion located above the high pressure air vessel, and that it further comprises a horizontal partition accommodated in the head portion and fixed to the lower end of the vertical partition (11 b) at the front end and to the lower end of the slanted rear side of the head portion at the rear end. a body portion for covering the part of the human body extending from the chest to the abdomen, a head portion for covering the part of a human body extending from the top of the head to the neck, which has a slanted rear side extending downward and rearward toward the rear side of the body portion opposing a high pressure air vessel accommodated in the chemical protective airtight suit, a pair of arm portions for covering the parts of the human body extending from the shoulders to the wrists, and a pair of leg portions for covering the parts of the human body extending from the abdomen to the calves, the aforementioned portions being integrated in a unitary body, and cooperating with a pair of gloves (α) for covering the parts of the human body extending from the wrists to the fingers and a pair of foot portions (β) for covering the parts of the human body extending from the calves to the toes so as to protect the whole human body, characterized in that the chemical protective airtight suit further comprises a vertical partition (11 b) accommodated in the head portion and fixed to the top of the head portion at the upper end and to either side of the head portion at either side end so as to divide the internal space of the head portion into a front portion for accommodating the head of the human body and a rear portion located above the high pressure air vessel, and that it further comprises a horizontal partition accommodated in the head portion and fixed to the lower end of the vertical partition (11 b) at the front end and to the lower end of the slanted rear side of the head portion at the rear end.