A light source unit includes a socket, a heat dissipation member, a board and a semiconductor light emitting element. The socket has a first thermal conductivity and includes a portion that defines a first side and a second side. The heat dissipation member has a second thermal conductivity being higher than the first thermal conductivity. The board is disposed on the first side. The semiconductor light emitting element is supported by the board. The socket is an injection-molded member. The heat dissipation member includes a first portion and a second portion. The first portion is disposed on the first side, extends in a first direction, and supports the board. The second portion includes a portion extending in a second direction intersecting with the first direction, as a result of being subjected to bending processing. A part of the second portion is disposed on the second side.