A laterally diffused metal oxide semiconductor (LDMOS) is provided. A substrate has a deep well with a second conductive type therein. A gate is disposed on the substrate. A first doped region of a second conductive type and a second doped region of a first conductive type are located in the deep well and at the corresponding two sides of the gate. A drain region of a second conductive type is located in the first doped region. A drain contact is disposed on the drain region. A doped region of a first conductive type is located in the first doped region and under the drain region but not directly below the drain contact. A source region is located in the second doped region. A field drift metal oxide semiconductor (FDMOS) which is similar to the laterally diffused metal oxide semiconductor (LDMOS) is also provided.