A data acquisition method of a substrate processing apparatus for acquiring data on gas current directions in a plurality of measurement regions on a surface of a substrate, includes: loading a sensing substrate having a plurality of pairs of sensors on a loader, wherein each pair of sensors includes a first sensor and a second sensor configured to acquire vector data of the gas current on the surface of the sensing substrate; acquiring vector data of the gas current in a first linear direction by the first sensor; acquiring vector data of the gas current in a second linear direction slanted to the first linear direction by the second sensor; and combining the gas current vectors based on a starting point associated with the respective pair of sensors; and calculating a gas current direction from the starting point associated with the respective pair of sensors.