A door latch device in a motor vehicle comprises an engagement portion which can engage with a striker of a vehicle body; an operating lever operated with a handle on a door of the vehicle to open the door; a locking lever which moves between an unlocking position where the engagement portion can be disengaged from the striker and a locked position where the engagement portion cannot be disengaged from the striker; a first subsidiary lever moving with the locking lever; a second subsidiary lever connected to the operating lever and moving with the first subsidiary lever; a spring exerting a force to the first subsidiary lever and the second subsidiary lever; and a blocking member moving between a blocking position and an unblocking position. When the blocking member is in the blocking position, a locking knob is actuated for unlocking to allow the locking lever and the first subsidiary lever to move from the locked position to the unlocking position against a force of the spring.