Differential pressure measuring device and differential pressure measurement method

A differential pressure measuring device measuring a differential pressure between a pressure in an on-floor area in a room in which a grating floor plate is placed and a pressure in an under-floor area in the room, comprising:

• a differential pressure measuring unit having a first port acquiring a pressure in the on-floor area, a second port acquiring a pressure in the under-floor area, a first pipe of which one end is connected to the first port, and a second pipe of which one end is connected to the second port;
• and
• a cup to which the other end of the second pipe is connected and which forms a space for measuring the pressure in the under-floor area on the grating floor plate when the grating floor plate is placed,
• wherein a distance in a device height direction between the other end of the first pipe and the other end of the second pipe is fixed.