A door lock device for holding a door in a fully-closed state, said door being capable of being opened and closed relative to a vehicle body, said door lock device comprising: a base plate and a striker which are installed to one and the other of said door and said vehicle body; a hook which is supported by said base plate to be rotatable between a striker holding position for holding said striker and a striker releasing position for releasing said striker, said hook being biased toward said striker releasing position; a latch which is supported by said base plate to be rotatable between a latching position at which said latch advances onto a rotating path of an engaging portion provided on said hook and an unlatching position at which said latch withdraws from said rotating path of said engaging portion of said hook; a latch controller which holds said latch in said latching position in each of a door-open state in which said hook is positioned in said striker releasing position and a door fully-closed state in which said hook is positioned in said striker holding position; prevents said hook from rotating toward said striker releasing position by engagement between said engaging portion of said hook and said latch in said door fully-closed state; and, when said latch controller performs a door opening operation from said door fully-closed state, makes said latch return to said latching position upon said hook reaching said striker releasing position after engagement between said latch and said hook has been released by causing said latch to rotate toward said unlatching position from said latching position; and a detector for detecting said door-open state; characterized in that said detector, during said door opening operation, detects that said door is open by referring to said returning operation of said latch to said latching position from said unlatching position that was performed by said latch controller. a base plate and a striker which are installed to one and the other of said door and said vehicle body; a hook which is supported by said base plate to be rotatable between a striker holding position for holding said striker and a striker releasing position for releasing said striker, said hook being biased toward said striker releasing position; a latch which is supported by said base plate to be rotatable between a latching position at which said latch advances onto a rotating path of an engaging portion provided on said hook and an unlatching position at which said latch withdraws from said rotating path of said engaging portion of said hook; a latch controller which holds said latch in said latching position in each of a door-open state in which said hook is positioned in said striker releasing position and a door fully-closed state in which said hook is positioned in said striker holding position; prevents said hook from rotating toward said striker releasing position by engagement between said engaging portion of said hook and said latch in said door fully-closed state; and, when said latch controller performs a door opening operation from said door fully-closed state, makes said latch return to said latching position upon said hook reaching said striker releasing position after engagement between said latch and said hook has been released by causing said latch to rotate toward said unlatching position from said latching position; and a detector for detecting said door-open state;