A pressure gauge of which the presence or absence of a measurement error can be easily checked is provided. A pressure gauge includes: a piston; a first conversion mechanism converting a linear motion of the piston against an elastic force of a spring into a rotating motion about a first rotation shaft, the linear motion being caused by the pressure transmitted from a target to be measured; an index that is fixed to one end side of the first rotation shaft; a dial; momentum detecting means for detecting momentum indicating an amount of movement of the piston; and a pressure sensor measuring a pressure value or the pressure acting on the internal space of the cylinder. Determining means determines whether a difference between a first measurement value and a second measurement value exceeds a predetermined value, the first measurement, value being estimated from the momentum detected toy the momentum detecting means, the second measurement value being measured by the pressure sensor. Notifying means notifies a user if the difference between the first measurement value and the second measurement value exceeds the predetermined value.