A hook apparatus is used to lift and convey a heavy structural member, e.g., an iron plate. The hook apparatus includes a hook support (1) having a fall preventing portion (11) at the distal end thereof and a wire securing portion (12) at the proximal end thereof, and a hook (3) whose proximal end portion has a bifurcate structure comprising two branch end portions (32 and 32'), the hook (3) being pivotably attached to the hook support (1) through a connecting pin (2) which extends between the branch end portions (32 and 32'), piercing through an approximately central portion (13) of the hook support (1) which is disposed in the space defined between the branch end portions (32 and 32'). The hook apparatus further includes a lock (4) disposed in the space defined between the branch end portions (32 and 32') of the hook (3) to cooperate with the approximately central portion (13) of the hook support (1) to lock the hook support (1) and the hook (3) to each other. The hook (3) is pivotable approximately 180.degree. reversely relative to the hook support (1) when the hook support (1) and the hook (3) are unlocked from each other by disengaging the lock (4). Thus, it is possible to lift, convey and release a heavy structural member extremely safely and efficiently.