An electrical junction box includes: a case; a relay; a first heat dissipation member connected to the relay; and a second heat dissipation member connected to the first heat dissipation member. The case includes a first case member, a second case member, a first coupling portion and a second coupling portion coupling the first case member to the second case member. The first case member, the first heat dissipation member, the second heat dissipation member, and the second case member are arranged in a stacked. The first coupling portion and the second coupling portion are arranged at an interval and are orthogonal with respect to the stack, the first heat dissipation member and the second heat dissipation member are interposed therebetween. The first coupling portion is disposed on an outer surface of the case, and the second coupling portion is on an inner surface of the case.