An electronic device comprising: a box-shaped housing ; a circuit substrate housed in the housing ; a connector that is mounted to the circuit substrate and that has a portion exposed to outside of the housing ; and a seal obtained by a sealant having fluidity being hardened, wherein the housing includes a lower case and an upper case that covers the lower case , the connector is disposed between the upper case and the lower case , the lower case has, in a surface on the upper case side of the lower case , a case groove that extends along a peripheral edge portion of the surface, the upper case has, on a surface on the lower case side of the upper case , a case projection that extends along a peripheral edge portion of the surface, the connector has a connector groove in a surface on the upper case side, and has a connector projection on a surface on the lower case side, the connector projection is fitted into the case groove and the case projection is fitted into the connector groove at a position at which the connector is disposed between the upper case and the lower case , the case projection is fitted into the case groove at a position at which the connector is not disposed between the upper case and the lower case , the seal is filled in a gap between the case groove and each of the case projection and the connector projection , and in a gap between the connector groove and the case projection , and projections disposed on a side wall of the case groove or the connector groove , the projections serving as an obstructor for inhibiting flow of the sealant, wherein, in the case groove or the connector groove , a plurality of the projections is aligned in a direction in which the groove extends, characterized in that a proportion of a width (Wp) of the projections to a distance (Dg) between the projections is not less than 5 % and not greater than 25 %. a box-shaped housing ; a circuit substrate housed in the housing ; a connector that is mounted to the circuit substrate and that has a portion exposed to outside of the housing ; and a seal obtained by a sealant having fluidity being hardened, wherein the housing includes a lower case and an upper case that covers the lower case , the connector is disposed between the upper case and the lower case , the lower case has, in a surface on the upper case side of the lower case , a case groove that extends along a peripheral edge portion of the surface, the upper case has, on a surface on the lower case side of the upper case , a case projection that extends along a peripheral edge portion of the surface, the connector has a connector groove in a surface on the upper case side, and has a connector projection on a surface on the lower case side, the connector projection is fitted into the case groove and the case projection is fitted into the connector groove at a position at which the connector is disposed between the upper case and the lower case , the case projection is fitted into the case groove at a position at which the connector is not disposed between the upper case and the lower case , the seal is filled in a gap between the case groove and each of the case projection and the connector projection , and in a gap between the connector groove and the case projection , and projections disposed on a side wall of the case groove or the connector groove , the projections serving as an obstructor for inhibiting flow of the sealant, wherein, in the case groove or the connector groove , a plurality of the projections is aligned in a direction in which the groove extends, characterized in that a proportion of a width (Wp) of the projections to a distance (Dg) between the projections is not less than 5 % and not greater than 25 %. <EOS>