There is provided a directly-coupled high-temperature superconductor SQUID magnetic sensor in a single thin film structure, which suppresses flux trapping or jumping generated in the sensor in a magnetic field, prevents the degradation in performance of the SQUID sensor, and operates stably with high sensitivity even in the magnetic field. The SQUID magnetic sensor including a bi-crystal substrate 1 having a bi-crystal grain boundary, pickup loops 7a-7d formed from a first high-temperature superconducting thin film on the bi-crystal substrate 1, and a SQUID ring 3 formed from the first high-temperature superconducting thin film on the bi-crystal grain boundary, directly connected with the pickup loops 7a-7d, wherein a plurality of pickup loops 7a-7d are disposed equally spaced from a bi-crystal grain boundary line 2 so as not to overlap with the bi-crystal grain boundary.