Planets at an early forming stage are deeply embedded in protoplanetary disks. To understand their formation, we need to directly observe and characterize such protoplanets. Since robust detections of accreting planets have been limited to PDS 70 bc to date, it remains still unclear how proto-giant planets receive mass from surroundings in detail. Recently Subaru/SCExAO discovered a new acceting protoplanet AB Aur b. In contrast to PDS 70 bc, AB Aur b’s H-alpha luminosity could be roughly 100 times brighter than PDS 70 bc, which suggests that AB Aur b is at earlier formation stage than that of PDS 70 bc. Here we present the results of follow-up observations of AB Aur b with VLT/MUSE integral field spectrograph at visible wavelengths. Our MUSE observations do not detect H-alpha from AB Aur b. This could be due to SDI data reduction. When a ratio of Halpha-to-continuum at a planet and a star is similar, the planet Halpha is well subtracted by SDI. Actually, Currie et al. (2022) reported that the ratio of Halpha-to-continuum at AB Aur and AB Aur b is similar. We note that our non-detection does not mean to rule out the presence of accretion of AB Aur b because of above reasons. We need other observations such as Pa-beta and Br-gamma to characterize accretion of AB Aur b. Meanwhile, we detected a ‘negative H-alpha disk’ around AB Aur. Hydrogen atom at the disk surface might be excited from n=1 to n=2 by Ly-alpha from the central star, and may absorb H-alpha at the disk surface. If this is true, the planet H-alpha might be also absorbed by the protoplanetary disk atmosphere, and thus, direct imaging of planet H-alpha embedded in the disk remains difficult to observe.