Pressure fluctuation is measured by using a condenser microphone and piezoresistive transducer. In order to confirm the experimental accuracy, measured data are compared with direct numerical simulation. This basic test encourages us to study small-scale statistics from the standpoint of Kohnogorov universal scaling. The power-law exponent and proportional constant of normalized pressure spectrum are discussed. The clear power law with scaling exponent -7/3 is confirmed in the range of R-lambda >= 600. These Reynolds numbers are much larger than those in velocity fluctuation for achieving the Kolmogorov scaling. The spectral constant K-p is not universal but depends on Reynolds number.