A semiconductor force sensor comprising: a semiconductor force sensor element including a diaphragm section having a converting section for converting a change in a force into a change in an electric signal by piezoresistive effect; force transmitting means (9, 33) for applying the force to be measured to said diaphragm section of said semiconductor force sensor element; and a force transmitting means positioning structure having an opposed wall section spaced from said diaphragm section and arranged to face said diaphragm section, for positioning and arranging said force transmitting means (9, 33) so that said force transmitting means (9, 33) is brought into direct contact with a central portion of said diaphragm section, said force transmitting means (9, 33) being constituted by a sphere having rigidity; wherein a through hole passing through said opposed wall section in a direction toward said diaphragm section is formed in said opposed wall section of said force transmitting means positioning structure at a position facing said central portion of said diaphragm section; and said through hole is so shaped that a part of said sphere faces an outside of said opposed wall section therethrough and receives a part of a remainder of said sphere so that said sphere can move only in a direction orthogonal to said diaphragm section and can rotate on said central portion of said diaphragm section, characterized in the that: a side of said diaphragm section on which said sphere is located is covered with a gel-like protective agent having electrically insulating property; and penetration of said gel-like protective agent is so defined that said sphere pushes away said gel-like protective agent on said diaphragm section to substantially come in direct contact with said central portion of said diaphragm section. a semiconductor force sensor element including a diaphragm section having a converting section for converting a change in a force into a change in an electric signal by piezoresistive effect; force transmitting means (9, 33) for applying the force to be measured to said diaphragm section of said semiconductor force sensor element; and a force transmitting means positioning structure having an opposed wall section spaced from said diaphragm section and arranged to face said diaphragm section, for positioning and arranging said force transmitting means (9, 33) so that said force transmitting means (9, 33) is brought into direct contact with a central portion of said diaphragm section, said force transmitting means (9, 33) being constituted by a sphere having rigidity; wherein a through hole passing through said opposed wall section in a direction toward said diaphragm section is formed in said opposed wall section of said force transmitting means positioning structure at a position facing said central portion of said diaphragm section; and said through hole is so shaped that a part of said sphere faces an outside of said opposed wall section therethrough and receives a part of a remainder of said sphere so that said sphere can move only in a direction orthogonal to said diaphragm section and can rotate on said central portion of said diaphragm section, characterized in the that: a side of said diaphragm section on which said sphere is located is covered with a gel-like protective agent having electrically insulating property; and penetration of said gel-like protective agent is so defined that said sphere pushes away said gel-like protective agent on said diaphragm section to substantially come in direct contact with said central portion of said diaphragm section. a side of said diaphragm section on which said sphere is located is covered with a gel-like protective agent having electrically insulating property; and penetration of said gel-like protective agent is so defined that said sphere pushes away said gel-like protective agent on said diaphragm section to substantially come in direct contact with said central portion of said diaphragm section.