A lamp unit for use in a vehicle lamp, the lamp unit comprising: a light source mounting portion on which a light source (16, 122, 132) is mounted; and a projector lens (100, 138) that is disposed on a vehicle front side of the light source (16, 122, 132), the projector lens includes an incident surface (100a, 138a) on which light emitted from the light source (16, 122, 132) is incident, a convex emission surface (100b, 138b) from which the light incident on the incident surface (100a, 138a) is emitted forwardly of the lamp, and a connection surface (100c, 138c) that connects an edge part of the incident surface (100a, 138a) and an edge part of the emission surface (100b, 138b), and characterized in that the connection surface (100c, 138c) includes, at least in a partial area thereof, a convex connection surface (100c1, 138cl) that is convex, in section including an optical axis, outward in a diameter direction of the projector lens (100, 138) such that the light emitted from the light source (16, 122, 132), incident on the incident surface (100, 138) and internally reflected by the convex connection surface (100c, 138c) reaches the emission surface (100b, 138b) with a larger incident angle than an incident angle with which light reaches a connection surface having a linear shape in section including the optical axis, so as to be apt to be totally reflected by the emission surface (100b, 138b) and not emitted forwardly from the emission surface (100b, 138b) of the projection lens (100, 138) when the lamp is mounted in the vehicle. a light source mounting portion on which a light source (16, 122, 132) is mounted; and a projector lens (100, 138) that is disposed on a vehicle front side of the light source (16, 122, 132), the projector lens includes an incident surface (100a, 138a) on which light emitted from the light source (16, 122, 132) is incident, a convex emission surface (100b, 138b) from which the light incident on the incident surface (100a, 138a) is emitted forwardly of the lamp, and a connection surface (100c, 138c) that connects an edge part of the incident surface (100a, 138a) and an edge part of the emission surface (100b, 138b), and an incident surface (100a, 138a) on which light emitted from the light source (16, 122, 132) is incident, a convex emission surface (100b, 138b) from which the light incident on the incident surface (100a, 138a) is emitted forwardly of the lamp, and a connection surface (100c, 138c) that connects an edge part of the incident surface (100a, 138a) and an edge part of the emission surface (100b, 138b), and characterized in that the connection surface (100c, 138c) includes, at least in a partial area thereof, a convex connection surface (100c1, 138cl) that is convex, in section including an optical axis, outward in a diameter direction of the projector lens (100, 138) such that the light emitted from the light source (16, 122, 132), incident on the incident surface (100, 138) and internally reflected by the convex connection surface (100c, 138c) reaches the emission surface (100b, 138b) with a larger incident angle than an incident angle with which light reaches a connection surface having a linear shape in section including the optical axis, so as to be apt to be totally reflected by the emission surface (100b, 138b) and not emitted forwardly from the emission surface (100b, 138b) of the projection lens (100, 138) when the lamp is mounted in the vehicle.