An isolator device comprising: a work chamber; air supply means for supplying air of a unidirectional airflow traveling from an upper part to a lower part in said work chamber; and air discharge means for discharging said unidirectional airflow from a lower part of said work chamber, characterized by having: a bulkhead provided in parallel with a peripheral wall portion of said work chamber along said air of unidirectional airflow; and a longitudinal air outlet opened along a width direction of a lower end portion in a lower part of the lower end portion of said bulkhead, wherein said air discharge means is provided with a filter unit for air purification detachably attached to a channel of air in said unidirectional airflow discharged from said longitudinal air outlet; said filter unit for air purification comprising: a parallel epipedic shaped body having a first wall portion provided with a longitudinal air inlet portion through which the unidirectional airflow travelling from the upper part to the lower part in the work chamber discharged from said air outlet is introduced and a second wall portion formed so as to cross said first wall portion and provided with an air discharge port portion through which the introduced air is discharged; and a filter member provided in said parallelepipedic shaped body and for filtering said introduced air, wherein said filter member is provided with its air discharge surface at said air discharge; and this filter unit for air purification is attached to the outside of the work chamber so as to oppose the air inlet portion to the air outlet; and a detachable lid body closing said air inlet portion; and a packing interposed in an airtight manner between an outer peripheral edge portion of this lid body and an inner peripheral edge portion of said air inlet portion. a work chamber; air supply means for supplying air of a unidirectional airflow traveling from an upper part to a lower part in said work chamber; and air discharge means for discharging said unidirectional airflow from a lower part of said work chamber, characterized by having: a bulkhead provided in parallel with a peripheral wall portion of said work chamber along said air of unidirectional airflow; and a longitudinal air outlet opened along a width direction of a lower end portion in a lower part of the lower end portion of said bulkhead, wherein said air discharge means is provided with a filter unit for air purification detachably attached to a channel of air in said unidirectional airflow discharged from said longitudinal air outlet; said filter unit for air purification comprising: a parallel epipedic shaped body having a first wall portion provided with a longitudinal air inlet portion through which the unidirectional airflow travelling from the upper part to the lower part in the work chamber discharged from said air outlet is introduced and a second wall portion formed so as to cross said first wall portion and provided with an air discharge port portion through which the introduced air is discharged; and a filter member provided in said parallelepipedic shaped body and for filtering said introduced air, wherein said filter member is provided with its air discharge surface at said air discharge; and this filter unit for air purification is attached to the outside of the work chamber so as to oppose the air inlet portion to the air outlet; and a parallel epipedic shaped body having a first wall portion provided with a longitudinal air inlet portion through which the unidirectional airflow travelling from the upper part to the lower part in the work chamber discharged from said air outlet is introduced and a second wall portion formed so as to cross said first wall portion and provided with an air discharge port portion through which the introduced air is discharged; and a filter member provided in said parallelepipedic shaped body and for filtering said introduced air, wherein said filter member is provided with its air discharge surface at said air discharge; and this filter unit for air purification is attached to the outside of the work chamber so as to oppose the air inlet portion to the air outlet; and a detachable lid body closing said air inlet portion; and a packing interposed in an airtight manner between an outer peripheral edge portion of this lid body and an inner peripheral edge portion of said air inlet portion.