Disclosed herein is a sensor. A sensor according to the present invention includes a mass body, a fixing part disposed so as to be spaced apart from the mass body, a first flexible part connecting the mass body with the fixing part in a Y-axis direction, a second flexible part connecting the mass body with the fixing part in an X-axis direction, and a membrane disposed over the second flexible part and having a width in a Y-axis direction larger than a width in a Y-axis direction of the second flexible part. Here, a width of an X-axis direction of the first flexible part is larger than a thickness in a Z-axis direction thereof and a thickness in a Z-axis direction of the second flexible part is larger than a width in a Y-axis direction thereof.