A blade protecting cap (50,50A,50B), configured to be detachably installed to an electric razor including an electric razor main body (12,13) and a blade portion provided in the electric razor main body (12,13), and configured to protect the blade portion, the blade protecting cap (50,50A,50B) comprising: a blade protecting cap main body configured to protect the blade portion by covering outer surfaces of the blade portion in an event where the blade protecting cap (50,50A,50B) is installed to the electric razor, wherein the blade protecting cap main body defines an inner space for inserting the blade portion, a first opening being formed in the blade protecting cap main body so that the first opening is allowed to communicate with an outer space of the blade protecting cap (50,50A,50B), protruding support portions capable of mounting the electric razor in a predetermined state on a mounting surface in an event where the blade protecting cap (50,50A,50B) abuts against the mounting surface with the electric razor having the blade protecting cap (50,50A,50B) installed thereto, wherein the support portions are protruded such that a space is formed of the blade protecting cap main body, the support portions and the mounting surface when the blade protecting cap (50,50A,50B) abuts against the mounting surface, and a second opening is formed by the space formed of the blade protecting cap main body, the support portions and the mounting surface, the space communicates with the outer space of the blade protecting cap (50,50A,50B), wherein, in the state where the support portions abut against the mounting surface the blade protecting cap main body has an inclined surface with respect to the mounting surface, and wherein, in the state where the support portions abut against the mounting surface, the first opening is formed in a lowermost portion of the inclined surface. a blade protecting cap main body configured to protect the blade portion by covering outer surfaces of the blade portion in an event where the blade protecting cap (50,50A,50B) is installed to the electric razor, wherein the blade protecting cap main body defines an inner space for inserting the blade portion, a first opening being formed in the blade protecting cap main body so that the first opening is allowed to communicate with an outer space of the blade protecting cap (50,50A,50B), protruding support portions capable of mounting the electric razor in a predetermined state on a mounting surface in an event where the blade protecting cap (50,50A,50B) abuts against the mounting surface with the electric razor having the blade protecting cap (50,50A,50B) installed thereto, wherein the support portions are protruded such that a space is formed of the blade protecting cap main body, the support portions and the mounting surface when the blade protecting cap (50,50A,50B) abuts against the mounting surface, and a second opening is formed by the space formed of the blade protecting cap main body, the support portions and the mounting surface, the space communicates with the outer space of the blade protecting cap (50,50A,50B), wherein, in the state where the support portions abut against the mounting surface the blade protecting cap main body has an inclined surface with respect to the mounting surface, and wherein, in the state where the support portions abut against the mounting surface, the first opening is formed in a lowermost portion of the inclined surface.