A semiconductor device comprising a lateral bipolar transistor, the lateral bipolar transistor including: a substrate including a first conductive layer; an active region located on the first conductive layer and having such a shape as to protrude from the first conductive layer and have an upper surface and at least two side surfaces opposing to each other in contact with the upper surface; and a device isolating oxide film partially covering said at least two side surfaces of the active region, wherein the active region includes a collector layer having a polarity different from that of the first conductive layer, and wherein the active region includes two intrinsic base layers having the same polarity as that of the first conductive layer wherein the two intrinsic base layers are formed at said side surfaces of the active region opposing to each other and are connected to each other via two extrinsic base layers that coalesce with each other at the top of the active region, wherein an emitter layer having the same polarity as that of the collector layer is formed in each of the intrinsic base layers at the side surfaces of the active region, wherein each emitter layer is connected to a respective emitter electrode, the lateral bipolar transistor further comprising a base electrode, wherein the extrinsic base layers are electrically connected to the base electrode, and further comprising at least two collector electrodes, wherein the collector layer is electrically connected to the collector electrodes, and said at least two collector electrodes are arranged on opposite sides of the active region in such a manner that a line connecting the collector electrodes is substantially orthogonal to another line connecting said two side surfaces of the active region at which the two intrinsic base layers are formed. a substrate including a first conductive layer; an active region located on the first conductive layer and having such a shape as to protrude from the first conductive layer and have an upper surface and at least two side surfaces opposing to each other in contact with the upper surface; and a device isolating oxide film partially covering said at least two side surfaces of the active region, wherein the active region includes a collector layer having a polarity different from that of the first conductive layer, and wherein the active region includes two intrinsic base layers having the same polarity as that of the first conductive layer wherein the two intrinsic base layers are formed at said side surfaces of the active region opposing to each other and are connected to each other via two extrinsic base layers that coalesce with each other at the top of the active region, wherein an emitter layer having the same polarity as that of the collector layer is formed in each of the intrinsic base layers at the side surfaces of the active region, wherein each emitter layer is connected to a respective emitter electrode, the lateral bipolar transistor further comprising a base electrode, wherein the extrinsic base layers are electrically connected to the base electrode, and further comprising at least two collector electrodes, wherein the collector layer is electrically connected to the collector electrodes, and said at least two collector electrodes are arranged on opposite sides of the active region in such a manner that a line connecting the collector electrodes is substantially orthogonal to another line connecting said two side surfaces of the active region at which the two intrinsic base layers are formed.