A laser light source device comprising: an optical unit that emits laser light; and a base member (BM1, BM1A, BM1B), wherein said optical unit includes a laser light emitting element that emits said laser light, and a lens through which the laser light transmits, said base member (BM1, BM1A, BM1B) is provided with a hole for retaining said optical unit, said base member (BM1, BM1A, BM1B) is further provided with a guide part (G1, G1v, G1A, G1x) used for determining a position of said laser light emitting element in said hole, a portion in said base member (BM1, BM1A, BM1B) that is in contact with said hole is provided with a retaining part that retains said laser light emitting element of said optical unit, said guide part (G1, G1v, G1A, G1x) and said hole are provided at a main surface (BMs) of said base member (BM1, BM1A, BM1B), said guide part (G1, G1v, G1A, G1x) is in contact with said hole, said laser light emitting element is inserted into said hole, said laser light source device is configured such that: said laser light emitting element can be inserted into said hole by a jig (80, 80A) designed for inserting the said laser light emitting element into said hole, said guide part (G1, G1v, G1A, G1x) has a shape fitting with a portion (X1, V1) of said jig (80, 80A), said shape of said guide part (G1, G1A) as seen in a plan view is elongated, and a shape of said hole as seen in a plan view is a circle, characterized in that said guide part (G1, G1A) is provided at said base member (BM1, BM1A) so as to extend along a long-side direction of the guide part (G1, G1A) and so as to prevent a center line that passes through a center in a short-side direction of the guide part (G1, G1A) from overlapping with a center of said hole as seen in a plan view. an optical unit that emits laser light; and a base member (BM1, BM1A, BM1B), wherein said optical unit includes a laser light emitting element that emits said laser light, and a lens through which the laser light transmits, said base member (BM1, BM1A, BM1B) is provided with a hole for retaining said optical unit, said base member (BM1, BM1A, BM1B) is further provided with a guide part (G1, G1v, G1A, G1x) used for determining a position of said laser light emitting element in said hole, a portion in said base member (BM1, BM1A, BM1B) that is in contact with said hole is provided with a retaining part that retains said laser light emitting element of said optical unit, said guide part (G1, G1v, G1A, G1x) and said hole are provided at a main surface (BMs) of said base member (BM1, BM1A, BM1B), said guide part (G1, G1v, G1A, G1x) is in contact with said hole, said laser light emitting element is inserted into said hole, said laser light source device is configured such that: said laser light emitting element can be inserted into said hole by a jig (80, 80A) designed for inserting the said laser light emitting element into said hole, said guide part (G1, G1v, G1A, G1x) has a shape fitting with a portion (X1, V1) of said jig (80, 80A), said shape of said guide part (G1, G1A) as seen in a plan view is elongated, and a shape of said hole as seen in a plan view is a circle, characterized in that said guide part (G1, G1A) is provided at said base member (BM1, BM1A) so as to extend along a long-side direction of the guide part (G1, G1A) and so as to prevent a center line that passes through a center in a short-side direction of the guide part (G1, G1A) from overlapping with a center of said hole as seen in a plan view. said laser light emitting element can be inserted into said hole by a jig (80, 80A) designed for inserting the said laser light emitting element into said hole, said guide part (G1, G1v, G1A, G1x) has a shape fitting with a portion (X1, V1) of said jig (80, 80A), said shape of said guide part (G1, G1A) as seen in a plan view is elongated, and a shape of said hole as seen in a plan view is a circle, characterized in that said guide part (G1, G1A) is provided at said base member (BM1, BM1A) so as to extend along a long-side direction of the guide part (G1, G1A) and so as to prevent a center line that passes through a center in a short-side direction of the guide part (G1, G1A) from overlapping with a center of said hole as seen in a plan view.