Load port, abnormal state determination method, and storage medium

An abnormal state determination method performed by a load port, the load port including a placement portion at which is placed a container accommodating a substrate, a plate that has an opening portion through which the substrate is inserted and removed, in a state in which the opening portion is adjacent to the container, a port door that opens and closes the opening portion and that includes an engaging portion configured to engage with an engagement portion of a lid of the container, a drive mechanism that moves the port door to an attachment position in a vicinity of the plate, a retracted position separated from the plate, and a detection position between the attachment position and the retracted position, a detection unit that detects at least the lid, and a control unit that controls an operation of each unit, the engaging portion protruding from a holding surface of the port door, a protrusion amount of the engaging portion being smaller than a thickness direction dimension of the lid that is held, and the lid having a second surface at an opposite side from a first surface, the first surface facing the port door, the method comprising:

• detecting, by the detection unit, a state of the lid attached to the container in a state in which the port door is moved from the attachment position to the detection position and the port door is stopped at the detection position;
• and
• determining a normal state or an abnormal state related to an attachment state of the lid based on a detection result of the detection unit,
• wherein the detecting includes a movement step of moving the drive mechanism to a position at which a detection region of the detection unit overlaps with a region between a tip portion of the engaging portion and the second surface of the lid in a case in which the first surface of the lid is contacting the holding surface of the port door.