A magnetic semiconductor material contains at least one type of transition metals (Mn2+, Fe3+, Ru3+, Re2+, and Os3+) having five electrons in the d atomic orbital as a magnetic ion, in which the magnetic semiconductor material exhibits n-type electrical conduction by injection of an electron carrier and p-type electric conduction by injection of a hole carrier. A specific example is a layered oxy-pnictide compound represented by LnMnOPn (wherein Ln is at least one type selected from Y and rare earth elements of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and Pn is at least one selected from pnicogen elements of N, P, As, Bi, and Sb). A high-sensitivity magnetic sensor, current sensor, or memory device can be made by using a magnetic pn homojunction structure made of thin films composed of the magnetic semiconductor material.