A piezoelectric sensor, characterized in that the piezoelectric sensor has an elongated-sheet shape and comprises: a piezoelectric layer containing an elastomer and piezoelectric particles; electrode layers (12a, 12b) which are disposed with the piezoelectric layer sandwiched between the electrode layers; and a protective layer (13a, 13b), wherein a product of Young's modulus and a thickness of the protective layer (13a, 13b) is larger than a product of Young's modulus and a thickness of the electrode layer (12a, 12b) adjacent to the protective layer, wherein, when a region in which the electrode layers overlap each other via the piezoelectric layer is set as a pressure sensing region, the pressure sensing region has a length of 500 mm or longer in a longitudinal direction thereof, wherein the electrode layers (12a, 12b) contain an elastomer and flaky conductive materials and are capable of elongating by 10% or more in one direction of plane directions, and when a space between one end portion and the other end portion of the pressure sensing region in the longitudinal direction is set as a measurement zone, an electrical resistance in the measurement zone in the electrode layers is 3,000 Ω or lower, and wherein, when the electrode layers (12a, 12b) disposed with one piezoelectric layer sandwiched therebetween are set as a first electrode layer and a second electrode layer, the following Expression is satisfied. Young's Modulus of Piezoelectric Layer 11 × Thickness of Piezoelectric Layer 11 ≥ Young's Modulus of First Electrode Layer 12 a × Thickness of First Electrode Layer 12 a + Young's Modulus of Second Electrode Layer 12 b × Thickness of Second Electrode Layer 12 b a piezoelectric layer containing an elastomer and piezoelectric particles; electrode layers (12a, 12b) which are disposed with the piezoelectric layer sandwiched between the electrode layers; and a protective layer (13a, 13b), wherein a product of Young's modulus and a thickness of the protective layer (13a, 13b) is larger than a product of Young's modulus and a thickness of the electrode layer (12a, 12b) adjacent to the protective layer, wherein, when a region in which the electrode layers overlap each other via the piezoelectric layer is set as a pressure sensing region, the pressure sensing region has a length of 500 mm or longer in a longitudinal direction thereof, wherein the electrode layers (12a, 12b) contain an elastomer and flaky conductive materials and are capable of elongating by 10% or more in one direction of plane directions, and when a space between one end portion and the other end portion of the pressure sensing region in the longitudinal direction is set as a measurement zone, an electrical resistance in the measurement zone in the electrode layers is 3,000 Ω or lower, and wherein, when the electrode layers (12a, 12b) disposed with one piezoelectric layer sandwiched therebetween are set as a first electrode layer and a second electrode layer, the following Expression is satisfied. Young's Modulus of Piezoelectric Layer 11 × Thickness of Piezoelectric Layer 11 ≥ Young's Modulus of First Electrode Layer 12 a × Thickness of First Electrode Layer 12 a + Young's Modulus of Second Electrode Layer 12 b × Thickness of Second Electrode Layer 12 b