A thick 25 μm thickness poled P(VDF/TrFE) film pyroelectric infrared ray sensor has been fabricated and then thin 1.6 μm thickness P(VDF/TrFE) film pyroelectric infrared ray sensor has been fabricated also. These thick and thin P(VDF/TrFE) film pyroelectric infrared ray sensor was mounted in TO-5 housing to detect infrared light of 5.5~14 μm wavelength for human body detecting with each other. The noise output voltage of the thick P(VDF/TrFE) film pyroelectric infrared ray sensor were 380 mV and NEP(noise equivalent power) is 3.95×10-7 W which is the similar value with the commercial pyroelectric nfrared ray sensor using ceramic materials as a sensing material. The NEP and specific detectivity D* of the thin P(VDF/TrFE) film pyroelectric infrared ray sensor were 2.13×10-8 W and 9.37×106 cm/W under emission energy of 13 μW/cm2 respectively. These result caused by lower thermal diffusion coefficient of a thin 1.6 μm thickness PVDF/TrFE film than the thick 25 μm thickness poled P(VDF/TrFE) film pyroelectric infrared ray sensor.