A position estimation system (10, 10', 10") for estimating a position of a hybrid vehicle (1, 1', 1") comprising an internal combustion engine, an electric motor, and a battery, comprising: a GNSS receiver; an object detection device for detecting an object in surroundings of the hybrid vehicle (1, 1', 1"), wherein the object detection device is an imaging device configured to capture an outside the hybrid vehicle (1, 1") and generate an image; an identifying part configured to identify the object detected by the object detection device; and a position estimating part configured to estimate a position of the hybrid vehicle (1, 1', 1") based on an output of the GNSS receiver, wherein if a predetermined condition is satisfied and the object identified by the identifying part is a sign indicating a boundary of a low emission zone which requires that the internal combustion engine be stopped, the position estimating part is configured to judge whether the hybrid vehicle (1, 1', 1") is located within the low emission zone, regardless of the output of the GNSS receiver, based on a result of identification by the identifying part, wherein the predetermined condition includes: a current driving environment of the hybrid vehicle (1, 1") not being a predetermined driving environment in which the precision of detection by the imaging device worsens; and the hybrid vehicle (1, 1', 1") being located in a vicinity of the low emission zone, wherein the hybrid vehicle is located in the vicinity of the low emission zone if a shortest distance between the position of the hybrid vehicle estimated based on the output of the GNSS receiver and the low emission zone within a predetermined time up to the present is equal to or less than a predetermined distance. a GNSS receiver; an object detection device for detecting an object in surroundings of the hybrid vehicle (1, 1', 1"), wherein the object detection device is an imaging device configured to capture an outside the hybrid vehicle (1, 1") and generate an image; an identifying part configured to identify the object detected by the object detection device; and a position estimating part configured to estimate a position of the hybrid vehicle (1, 1', 1") based on an output of the GNSS receiver, wherein if a predetermined condition is satisfied and the object identified by the identifying part is a sign indicating a boundary of a low emission zone which requires that the internal combustion engine be stopped, the position estimating part is configured to judge whether the hybrid vehicle (1, 1', 1") is located within the low emission zone, regardless of the output of the GNSS receiver, based on a result of identification by the identifying part, wherein the predetermined condition includes: a current driving environment of the hybrid vehicle (1, 1") not being a predetermined driving environment in which the precision of detection by the imaging device worsens; and the hybrid vehicle (1, 1', 1") being located in a vicinity of the low emission zone, wherein the hybrid vehicle is located in the vicinity of the low emission zone if a shortest distance between the position of the hybrid vehicle estimated based on the output of the GNSS receiver and the low emission zone within a predetermined time up to the present is equal to or less than a predetermined distance. a current driving environment of the hybrid vehicle (1, 1") not being a predetermined driving environment in which the precision of detection by the imaging device worsens; and the hybrid vehicle (1, 1', 1") being located in a vicinity of the low emission zone, wherein the hybrid vehicle is located in the vicinity of the low emission zone if a shortest distance between the position of the hybrid vehicle estimated based on the output of the GNSS receiver and the low emission zone within a predetermined time up to the present is equal to or less than a predetermined distance.