An electrical connection box includes a block that houses a plurality of electronic components, a housing body in which an internal space for housing the block is formed, and engagement portions that are provided between the block and the housing body and fits the block to the housing body. The engagement portions include a first engagement portion corresponding to the one direction end of the block in a specific direction and a second engagement portion corresponding to the other direction end of the block in the specific direction. In the first engagement portion, an inclined surface of the guide receiving portion is formed. When the block is inserted into the housing body in the insertion direction, the inclined surface is formed by cutting out an end where the guide receiving portion faces a guide piece in the insertion direction.