A power source apparatus comprising: a plurality of battery modules; a housing constituting a housing chamber configured to house and arrange the battery modules in parallel and housing the battery modules; a blower configured to blow air; and a chassis storing the blower and the housing inside, characterized in that the chassis includes: a main body having a bottom wall, a side wall standing up from a circumference of the bottom wall, and a flange portion disposed on a standing end portion of the side wall; and a lid configured to be fixed to the flange portion of the main body, wherein the housing has a bracket including a bottom plate, a side plate, extending portions, and a cover, wherein the cover is arranged above the battery modules, wherein the battery modules are arranged between the cover and the bottom plate of the bracket, wherein the bottom plate is arranged below the battery modules, wherein the side plate includes: a first side plate standing up from one of edge portions of the bottom plate; and a second side plate standing up from the other one of the edge portions of the bottom plate, the other one of the edge portions being opposed to the one of the edge portions, wherein the extending portions are located above the flange portion and disposed on standing end portions of the first side plate and the second side plate, extend in a direction separating from each other, and have fastening portions configured to be fastened to the flange portion, wherein a sending portion that is an opening portion is formed on the bottom plate and configured to send the air staying in the housing chamber to the outside of the housing chamber, wherein the cover includes an intake portion configured to take the air toward the battery modules, the air being blown from the blower, wherein the bottom plate of the bracket includes the sending portion configured to send the air, the air being taken from the intake portion and having passed through the battery modules, wherein the bracket includes a first fixing portion standing up from the bottom plate, wherein the cover includes a second fixing portion configured to be fixed to the first fixing portion and wherein the plurality of battery modules are sandwiched and supported between the cover and the bottom plate with the first fixing portion and the second fixing portion being fixed to each other. a plurality of battery modules; a housing constituting a housing chamber configured to house and arrange the battery modules in parallel and housing the battery modules; a blower configured to blow air; and a chassis storing the blower and the housing inside, characterized in that the chassis includes: a main body having a bottom wall, a side wall standing up from a circumference of the bottom wall, and a flange portion disposed on a standing end portion of the side wall; and a lid configured to be fixed to the flange portion of the main body, a main body having a bottom wall, a side wall standing up from a circumference of the bottom wall, and a flange portion disposed on a standing end portion of the side wall; and a lid configured to be fixed to the flange portion of the main body, wherein the housing has a bracket including a bottom plate, a side plate, extending portions, and a cover, wherein the cover is arranged above the battery modules, wherein the battery modules are arranged between the cover and the bottom plate of the bracket, wherein the bottom plate is arranged below the battery modules, wherein the side plate includes: a first side plate standing up from one of edge portions of the bottom plate; and a second side plate standing up from the other one of the edge portions of the bottom plate, the other one of the edge portions being opposed to the one of the edge portions, a first side plate standing up from one of edge portions of the bottom plate; and a second side plate standing up from the other one of the edge portions of the bottom plate, the other one of the edge portions being opposed to the one of the edge portions, wherein the extending portions are located above the flange portion and disposed on standing end portions of the first side plate and the second side plate, extend in a direction separating from each other, and have fastening portions configured to be fastened to the flange portion, wherein a sending portion that is an opening portion is formed on the bottom plate and configured to send the air staying in the housing chamber to the outside of the housing chamber, wherein the cover includes an intake portion configured to take the air toward the battery modules, the air being blown from the blower, wherein the bottom plate of the bracket includes the sending portion configured to send the air, the air being taken from the intake portion and having passed through the battery modules, wherein the bracket includes a first fixing portion standing up from the bottom plate, wherein the cover includes a second fixing portion configured to be fixed to the first fixing portion and wherein the plurality of battery modules are sandwiched and supported between the cover and the bottom plate with the first fixing portion and the second fixing portion being fixed to each other.