In a head protection airbag device according to the invention, non-inflating portions of an airbag includes a blocking portion which covers the vehicle interior side of windows when inflation of the airbag is completed. One blocking portion includes a downward movement inhibiting portion catching a passenger's head and inhibiting its downward movement when the head moves downward while moving toward the vehicle exterior and touches the blocking portion when inflation of the airbag is completed. The blocking portion comprises overlapping vehicle interior side and the vehicle exterior side portions which are mutually connected, with a portion of a vehicle interior member by the upper edge made to be the downward movement inhibiting portion. The downward movement inhibiting portion is connected at both the front and rear edges to the vehicle exterior member of the blocking portion, allowing the upper edge of the downward movement inhibiting portion to be a catching edge which can be separated from the vehicle exterior member when catching the head.