A pressure sensor is provided. The pressure sensor includes a sensing element, a case, a line element, an insect entering restriction element. The case has a space for receiving the sensing element. The case includes a pressure introduction passage, which is in communication with the space to introduce a pressure medium into the sensing element. The line element has a first portion electrically connected with the sensing element and a second portion to be electrically connected to an external element. The insect entering restriction element extends across a path on the exterior surface of the case, the path interconnecting between the second portion of the line element and the open end of pressure introduction passage.