A transistor with a shared gate structure includes an active area and a gate. The active area has a body extending in a first direction on a substrate, and a protrusion extending in a second direction perpendicular to the first direction from a central portion of the body in the first direction. The gate is arranged above the active area to overlap a channel area of the active area, and has an inverted pi (II) structure that, from a plan view, surrounds on three sides but does not cover a portion of the active area that includes two corner portions of the active area. The active area is divided into a first active area and a second active area by a separation area extending in the second direction and separating the body and a portion of the protrusion. The protrusion is divided into a first portion separated into two sub-portions by the separation area and a second portion, wherein the first portion is between the body and the second portion in the second direction. Opposite ends of the body in the first direction corresponding to two drain areas, the second portion of the protrusion corresponding to a common source area, and the gate constitute two transistors, wherein the two transistors share the gate.