Provided are a semiconductor element and a semiconductor device capable of reducing possibilities of malfunctions and breakdowns due to temperature rise. A semiconductor element (50) includes a first MOS transistor (Tr1), a second MOS transistor (Tr2), and a temperature detecting element (TD) that are provided on a semiconductor substrate (SB). The first MOS transistor (Tr1) includes an n-type source region (8), an n-type first semiconductor region (21) arranged away from the source region (8) and a p-type well region (31) arranged between the source region (8) and the first semiconductor region (21). The second MOS transistor (Tr2) includes an n-type source region (8) an n-type second semiconductor region (22) arranged away from the source region (8), and a p-type well region (31) arranged between the source region (8) and the second semiconductor region (22). The first semiconductor region (21) is connected to the second semiconductor region (22).