The present paper discusses experimental and numerical studies on the fluid behavior in a magnetohydrodynamic(MHD) micro pump for micro total analysis system(${mu}$-TAS). In the experiment, the MHD micro pump has a length of 26.0 mm, a width and a height of 0.5 mm. As a working fluid, Phosphate Buffered Saline(PBS) solution is used under the assumption of blood analysis using ${mu}$-TAS. A neodymium permanent magnet with the maximum magnetic flux density of 0.32 T is used for applying a magnetic field to a channel in the MHD pump. Experimental and numerical results show that Hartmann flow is not observed in the channel because the MHD interaction is very weak, so that Poiseuille flow is maintained in the channel. The numerical study also examines the influences of the channel height and the strength of externally applied magnetic flux density on the fluid temperature in the channel. The numerical results indicate that an increase in fluid temperature by operating the MHD pump is less than 1 K when the magnetic flux density and the channel height are more than 0.3 T and 0.3 mm, respectively.