A system comprising: a dental syringe; and a dental syringe holder, comprising: a syringe holding portion that attachably and detachably holds an outer barrel of the dental syringe; and a clamping wing portion that is formed on an outer periphery of the syringe holding portion, and is configured to be clamped by a forefinger and a middle finger in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, and a placing wing portion which is formed on the outer periphery of the syringe holding portion, and is configured so as to allow a thumb to be placed on it in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, wherein in a projected image on a plane orthogonal to an axial direction of the syringe, an angle (θ) that is formed by a first line segment connecting a center of a minimum virtual circle that surrounds the outer periphery of the syringe holding portion and a formation position of the clamping wing portion, and a second line segment connecting the center of the virtual circle and a formation position of the placing wing portion is in a range from 90° to 170° inclusive. a dental syringe; and a dental syringe holder, comprising: a syringe holding portion that attachably and detachably holds an outer barrel of the dental syringe; and a clamping wing portion that is formed on an outer periphery of the syringe holding portion, and is configured to be clamped by a forefinger and a middle finger in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, and a placing wing portion which is formed on the outer periphery of the syringe holding portion, and is configured so as to allow a thumb to be placed on it in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, a syringe holding portion that attachably and detachably holds an outer barrel of the dental syringe; and a clamping wing portion that is formed on an outer periphery of the syringe holding portion, and is configured to be clamped by a forefinger and a middle finger in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, and a placing wing portion which is formed on the outer periphery of the syringe holding portion, and is configured so as to allow a thumb to be placed on it in the case of holding the dental syringe with three fingers that are the thumb, the forefinger and a middle finger in such a manner as to hold a pen, wherein in a projected image on a plane orthogonal to an axial direction of the syringe, an angle (θ) that is formed by a first line segment connecting a center of a minimum virtual circle that surrounds the outer periphery of the syringe holding portion and a formation position of the clamping wing portion, and a second line segment connecting the center of the virtual circle and a formation position of the placing wing portion is in a range from 90° to 170° inclusive.