The invention relates to a sidewise sliding door control device and a control method of the sidewise sliding door control device. Due to the fact that the obstacle detection function is added, the phenomenon that when passengers get on a train and get off the train, the passengers are clamped by a sidewise sliding door and are injured can be avoided, and safety of the passengers is improved when the passengers get on the train and get off the train; due to the fact that door opening and closing signals output by a door mechanism controller are connected to contacts of a door opening and closing relay of a switchboard in parallel, and if obstacles do not exist, the door mechanism controller cannot have an influence on door opening and closing operation, namely, the door opening and closing operation is only controlled through door opening and closing instructions from the switchboard; due to the fact that parallel connection is carried out, even when the door mechanism controller has a fault, normal door opening and closing operation cannot be influenced, only the obstacle detection function is lost, and reliability of the door opening and closing operation is improved; due to the fact that when the speed per hour of the train is larger than 5KM or the door is closed in place or the door is pressed, a CPU control system cannot execute any motion, the phenomenon that due to faults of input signals, malfunction of a door mechanism control system happens can be avoided, and safety and reliability of a door opening and closing system are improved.