Pressure sensing device and blood purification apparatus using same

A pressure sensing device, comprising:

• a case provided on a liquid flow path through which a liquid subject to pressure measurement flows;
• a diaphragm that is provided so as to divide a space in the case into a first space with the liquid flowing therethrough and a second space filled with a gas and can be displaced according to pressure of the liquid is the first space;
• a pressure sensor to measure pressure of the gas filling the second space;
• and
• a diaphragm initial position adjustment mechanism capable of adjusting an initial position of the diaphragm to a desired position by adjusting a filling amount of the gas filling the second space,
• wherein the diaphragm initial position adjustment mechanism comprises a reciprocating pump that comprises a cylinder in communication with the second space, a plunger provided so as to be able to advance and retract within the cylinder, and a plunger driving part to advance and retract the plunger, and adjusts a filling amount of the gas filling the second space by advancing and retreating the plunger in the cylinder by the plunger driving part.